Light emitting element, light emitting device and electronic apparatus

ABSTRACT

The light emitting element of the embodiment includes an anode; a cathode; a visible light emitting layer provided between the anode and the cathode and emitting visible light; and a carrier trapping layer containing a thiadiazole based compound represented by the following formula (1). 
     
       
         
         
             
             
         
       
     
     [In formula (1), A indicates a hydrogen atom, an alkyl group, an aryl group which may have a substituent, an arylamino group, or a triaryl amine, and B indicates a hydrogen atom, an alkyl group, an aryl group which may have a substituent, an arylamino group, or a triaryl amine, or may form a ring.]

This is a Continuation of application Ser. No. 13/727,339 filed Dec. 26,2012, which claims the benefit of Japanese Patent Application No.2011-289851 filed Dec. 28, 2011. The disclosures of the priorapplications are hereby incorporated by reference herein in theirentirety.

BACKGROUND

1. Technical Field

The present invention relates to a light emitting element, a lightemitting device and an electronic apparatus.

2. Related Art

An organic electroluminescent device (commonly called an organic ELelement) is a light emitting element having a structure in which atleast one layer of a luminescent organic layer is interposed between ananode and a cathode. In such a light emitting element, by applying anelectric field between the cathode and the anode, electrons are injectedfrom the cathode side into the light emitting layer and, along withthis, holes are injected from the anode side, excitons are generated bythe recombination of the electrons and the holes in the light emittinglayer, and, when the excitons return to a ground state, the energyportion thereof is released as light.

The luminance life span in the above light emitting elements shows atendency to vary according to the luminescent color emitted as light bythe light emitting layer, and it is known that, specifically, theshorter the wavelength of the luminescent color, the shorter the lifespan.

For example, as one of the causes of this tendency, the following may beconsidered.

That is, it has been found that the shorter the wavelength of theluminescent color of the light emitting layer provided in the lightemitting element, the easier the balance of the carrier (the holes andthe electrons) flowing inside the light emitting element is lost and thestronger the tendency to excessively generate the carrier, as the usetime of the light emitting element increases. For this reason, in a casewhere one or both of a hole transporting layer and an electrontransporting layer are provided, for example, to be adjacent to thelight emitting layer, in the above layers, there is a tendency forelectrons or holes which have come through the light emitting layer tobe injected, and, as a result, it is supposed that the degradation ofthe configurational material configuring the above layer is promoted.

As a configuration of the light emitting element solving the aboveproblem, there has been proposed a configuration provided with a lightemitting layer emitting red luminescent color of a longer wavelength inaddition to a light emitting layer emitting (blue) luminescent color ofa short wavelength.

That is, it has been proposed that, by configuring the light emittingelement to be provided with a plurality of layers emitting shortwavelength luminescent color and layers emitting long wavelengthluminescent color as light emitting layers, a lengthening of the lifespan of the light emitting element is achieved (for example, refer toJP-A-2007-115626).

However, because long wavelength luminescent color (for example, red) isalso naturally emitted from the light emitting element having the aboveconfiguration, in a case where it is necessary to set only shortwavelength luminescent color (for example, blue) as the luminescentcolor emitted by the light emitting element, since there is a need toprovide a color filter absorbing long wavelength luminescent color,there are problems in that the element configuration of the lightemitting element becomes complicated and this leads to an increase inthe number of processes when manufacturing the light emitting element.

SUMMARY

An advantage of some aspects of the invention is to provide a lightemitting element provided with a light emitting layer emitting visiblelight with a long life span without changing the chromaticity, and alight emitting device and an electronic apparatus provided with theabove light emitting element.

The aspects of the invention are achieved by the following invention.

According to an aspect of the invention, there is provided a lightemitting element includes: an anode; a cathode; a light emitting layerprovided between the anode and the cathode and emitting visible light;and a carrier trapping layer containing a thiazole based compoundrepresented by the following formula (1).

[In formula (1), A indicates a hydrogen atom, an alkyl group, an arylgroup which may have a substituent, an arylamino group, or a triarylamine, and B indicates a hydrogen atom, an alkyl group, an aryl groupwhich may have a substituent, an arylamino group, or a triaryl amine, ormay form a ring.]

In this manner, without changing the chromaticity, it is possible to seta light emitting element provided with a light emitting layer emittingvisible light with a long life span.

It is preferable that the thiadiazole based compound be represented bythe following formula (1B).

[In formula (1B), A's each independently indicate a hydrogen atom, analkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The thiadiazole based compound of the above configuration has energylevels capable of trapping carriers, and the light generated as a resultat the time of returning to the ground state is in the near infraredregion. Accordingly, it is possible to trap the carrier coming throughthe light emitting layer, and it is possible to set a light emittingelement provided with a light emitting layer emitting visible light witha long life span without changing the chromaticity of the visible light.

It is preferable that the thiadiazole based compound be represented bythe following formula (1C).

[In formula (1C), A's each independently indicate a hydrogen atom, analkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The thiadiazole based compound of the above configuration has energylevels capable of trapping carriers, and the light generated as a resultat the time of returning to the ground state is in the near infraredregion. Accordingly, it is possible to trap the carrier coming throughthe light emitting layer, and it is possible to set a light emittingelement provided with a light emitting layer emitting visible light witha long life span without changing the chromaticity of the visible light.

It is preferable that the thiadiazole based compound be represented bythe following formula (1D).

[In formula (1 D), A and B each independently indicate a hydrogen atom,an alkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The thiadiazole based compound of the above configuration has energylevels capable of trapping carriers, and the light generated as a resultat the time of returning to the ground state is in the near infraredregion. Accordingly, it is possible to trap the carrier coming throughthe light emitting layer, and it is possible to set a light emittingelement provided with a light emitting layer emitting visible light witha long life span without changing the chromaticity of the visible light.

It is preferable that the carrier trapping layer be positioned at theanode side relative to the light emitting layer.

In this manner, electrons which have come through the light emittinglayer are trapped and it is possible to suppress or prevent theelectrons being injected into the anode side. Therefore, it is possibleto accurately suppress or prevent the alteration or degradation of theconstituent material of the layer positioned further toward the anodeside than the carrier trapping layer, and, as a result, a lengthening ofthe life span of the light emitting element can be achieved.

It is preferable that the carrier trapping layer further contain a hostmaterial in addition to the thiazole based compound, and that the hostmaterial be at least one type from among amine based material,anthracene based material and naphthacene based material.

Since the above materials are excellent in hole transportability andexcellent in resistance to electrons and holes, it is possible toachieve a lengthening of the life span while providing the carriertrapping layer with a function as a hole transporting layer.

It is preferable that the carrier trapping layer be positioned furthertoward the cathode side than the light emitting layer.

In this manner, it is possible to trap the holes coming through thelight emitting layer and suppress or prevent the holes from beinginjected into the cathode side. Therefore, it is possible to accuratelysuppress or prevent the alteration or degradation of the constituentmaterial of the layer positioned further toward the cathode side thanthe carrier trapping layer, and, as a result, a lengthening of the lifespan of the light emitting element can be achieved.

It is preferable that the carrier trapping layer further contain a hostmaterial in addition to the thiazole based compound, and that the hostmaterial be at least one type from among anthracene based material,naphthacene based material and quinolinolate based material.

Since the above materials are excellent in electron transportability andexcellent in resistance to electrons and holes, it is possible toachieve a lengthening of the life span while providing the carriertrapping layer with a function as an electron transporting layer.

It is preferable that the light emitting layer be one layer.

It is possible to apply the light emitting element according to theaspect of the invention to the light emitting element having the aboveconfiguration.

It is preferable that the light emitting layer emit a blue luminescentcolor as visible light.

As such a light emitting layer, when a layer emitting blue luminescentlight is provided in the light emitting element, by applying the lightemitting element according to an aspect of the invention, it is possibleto achieve a lengthening of the life span of the light emitting layeremitting blue luminescent light, which is a light emitting layer havinga short life′ span.

It is preferable that the light emitting layer emit yellow luminescentcolor as visible light.

As such a light emitting layer, when a layer emitting yellow luminescentlight is provided in the light emitting element, by applying the lightemitting element according to an aspect of the invention, it is possibleto achieve a lengthening of the life span of the light emitting layeremitting yellow luminescent light, which is a light emitting layerhaving a short life span.

It is preferable that the light emitting layer be formed of at least twolayers.

It is possible to apply the light emitting element according to anaspect of the invention to the light emitting element having the aboveconfiguration.

According to another aspect of the invention, there is provided a lightemitting device including the light emitting element according to theaspect of the invention.

In this manner, it is possible to set a light emitting device havingexcellent reliability.

According to still another aspect of the invention, there is provided anelectronic apparatus including the light emitting device according to anaspect of the invention.

In this manner, it is possible to set an electronic apparatus havingexcellent reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a view schematically showing a longitudinal section in a firstembodiment of the light emitting element according to an aspect of theinvention.

FIG. 2 is a view schematically showing a longitudinal section in asecond embodiment of the light emitting element according to an aspectof the invention.

FIG. 3 is a view schematically showing a longitudinal section in a thirdembodiment of the light emitting element according to an aspect of theinvention.

FIG. 4 is a view schematically showing a longitudinal section in afourth embodiment of the light emitting element according to an aspectof the invention.

FIG. 5 is a view schematically showing a longitudinal section in a fifthembodiment of the light emitting element according to an aspect of theinvention.

FIG. 6 is a view schematically showing a longitudinal section in a sixthembodiment of the light emitting element according to an aspect of theinvention.

FIG. 7 is a view schematically showing a longitudinal section in aseventh embodiment of the light emitting element according to an aspectof the invention.

FIG. 8 is a view showing an embodiment of an illumination light sourceapplying the light emitting device according to an aspect of theinvention.

FIG. 9 is a view showing an embodiment of a display apparatus in whichthe light emitting device according to an aspect of the invention isapplied.

FIG. 10 is a perspective view showing a configuration of a mobile type(or a notebook type) personal computer in which the electronic apparatusaccording to an aspect of the invention is applied.

FIG. 11 is a view showing the light emitting spectra in the lightemitting elements of Examples 1 to 4.

FIG. 12 is a view showing the light emitting spectra in the lightemitting elements of Examples 5 to 8.

FIG. 13 is a view showing the light emitting spectra in the lightemitting elements of Examples 9, and 13 to 15.

FIG. 14 is a view showing the light emitting spectra in the lightemitting elements of Examples 17 and 10, and Comparative Examples 1 and2.

FIG. 15 is a view showing the light emitting spectra in the lightemitting elements of Examples 11 and 12, and Comparative Examples 3 and4.

FIG. 16 is a view showing the light emitting spectra in the lightemitting elements of Example 16, and Comparative Example 5.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Below, description will be given of the light emitting element, lightemitting device and electronic apparatus according to an aspect of theinvention in suitable embodiments shown in the attached drawings.

First Embodiment

First, description will be given of a first embodiment of the lightemitting element according to an aspect of the invention.

FIG. 1 is a cross-sectional view schematically showing the firstembodiment of the light emitting element according to an aspect of theinvention. Here, in the following, for convenience of description,description is given with the upper side in FIG. 1 as “up” and the lowerside as “down”.

The light emitting element (electroluminescence element) 1 shown in FIG.1 is one in which an anode 3, a hole injection layer 4, a holetransporting layer 5, a carrier trapping layer 6, a red light emittinglayer 7R, an intermediate layer 8, a blue light emitting layer 7B, agreen light emitting layer 7G, an electron transporting layer 9, anelectron injection layer 10, and a cathode 11 are laminated in thisorder. That is, in the light emitting element 1, between the anode 3 andthe cathode 11, a laminate body 14 in which, from the anode 3 to thecathode 11, the hole injection layer 4, the hole transporting layer 5,the carrier trapping layer 6, the red light emitting layer 7R, theintermediate layer 8, the blue light emitting layer 7B, the green lightemitting layer 7G, the electron transporting layer 9, and the electroninjection layer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on asubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to each lightemitting layer of the red light emitting layer 7R, the blue lightemitting layer 7B, and the green light emitting layer 7G, electrons aresupplied (injected) from the cathode 11 side and, along with this, holesare supplied (injected) from the anode 3 side. Thus, in each lightemitting layer, the holes and the electrons are recombined, excitons aregenerated by the energy released during the recombination, and energy(fluorescence and phosphorescence) is released when the excitons returnto the ground state. Therefore, the red light emitting layer 7R, theblue light emitting layer 7B, and the green light emitting layer 7Grespectively emit red, blue, and green visible light. In this manner,the light emitting element 1 emits white visible light. Here, in thepresent embodiment, the light emitting layer (visible light emittinglayer) 7 emitting visible light is configured by the three layers of thered light emitting layer 7R, the blue light emitting layer 7B, and thegreen light emitting layer 7G.

In addition, in the present embodiment, since the light emitting element1 has a carrier trapping layer 6 between the red light emitting layer 7Rand the hole transporting layer 5, electrons coming through the redlight emitting layer 7R are injected into the hole transporting layer 5side, whereby it is possible to accurately suppress or prevent thealteration or degradation of the constituent material of the holetransporting layer 5 and the hole injection layer 4, and, as a result,it is possible to achieve a lengthening of the life span of the lightemitting element 1.

Furthermore, in the present embodiment, since the light emitting element1 has an intermediate layer 8 between the red light emitting layer 7Rand the blue light emitting layer 7B, it is possible to adjust themovement of the holes and electrons between the red light emitting layer7R and the blue light emitting layer 7B, whereby it is possible toprevent energy movement of excitons between the red light emitting layer7R and the blue light emitting layer 7B. As a result, the red lightemitting layer 7R and the blue light emitting layer 7B respectively emitlight with good balance, whereby the light emitting element 1 emitswhite light as visible light more reliably.

The substrate 2 supports the anode 3. Since the light emitting element 1of the present embodiment has a configuration (bottom emission type)extracting light from the substrate 2 side, the substrate 2 and theanode 3 are respectively set to be substantially transparent (colorlessand transparent, colored and transparent, or semi-transparent).

Examples of the constituent materials of the substrate 2 include resinmaterials such as polyethylene terephthalate, polyethylene naphthalate,polypropylene, cycloolefin polymer, polyamide, polyether sulfone,polymethyl methacrylate, polycarbonate, and polyarylate; glass materialssuch as quartz glass and soda glass; and the like, and it is possible touse one type or a combination of two or more types from the above.

The average thickness of the substrate 2 is not particularly limited;however, approximately 0.1 to 30 mm is preferable, and approximately 0.1to 10 mm is more preferable.

Here, in a case of a configuration (top emission type) where the lightemitting element 1 extracts light from the opposite side of thesubstrate 2, it is possible to use either of a transparent substrate oran opaque substrate as the substrate 2.

Examples of the opaque substrate include substrates configured byceramic material such as alumina, those in which an oxide film(insulator film) on the surface of a substrate of metal such asstainless steel, substrates configures of resin materials, and the like.

Further, in the above light emitting element 1, the distance between theanode 3 and the cathode 11 (that is, the average thickness of thelaminate body 14) is preferably 100 to 500 nm, more preferably 100 to300 nm, and even more preferably 100 to 250 nm. In this manner, it ispossible to easily and reliably set the driving voltage of the lightemitting element 1 within a practical range.

Below, each part configuring the light emitting element 1 will bedescribed in sequence. Anode

The anode 3 is an electrode injecting holes into the hole transportinglayer 5 through the hole injection layer 4 to be described later. Asconstituent materials of the anode 3, it is preferable to use materialshaving a large work function and having excellent conductivity.

Examples of the constituent material of the anode 3 include oxides suchas ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In₃O₃, SnO₂, SnO₂containing Sb, and ZnO containing Al, Au, Pt, Ag, Cu or alloys or thelike including these metals, and it is possible to use one type or acombination of two or more types from the above.

In particular, the anode 3 is preferably configured by ITO. ITO is amaterial which, in addition to having transparency, has a large workfunction and excellent conductivity. In this manner, it is possible toefficiently inject holes into the hole injection layer 4 from the anode3.

In addition, the surface (upper surface in FIG. 1) of the hole injectionlayer 4 side of the anode 3 preferably undergoes a plasma treatment. Inthis manner, it is possible to increase the chemical and mechanicalstability of the bonding surfaces of the anode 3 and the hole injectionlayer 4. As a result, it is possible to improve the hole injectionproperty into the hole injection layer 4 from the anode 3. Here,regarding the plasma treatment, detailed description will be given inthe description of the method of manufacturing the light emittingelement 1 to be described later.

The average thickness of such an anode 3 is not particularly limited;however, approximately 10 to 200 nm is preferable and approximately 50to 150 nm is more preferable. Cathode

On the other hand, the cathode 11 is an electrode which injectselectrons into the electron transporting layer 9 through the electroninjection layer 10 to be described later. As the constituent material ofthe cathode 11, it is preferable to use material with a small workfunction.

Examples of the constituent material of the cathode 11 include Li, Mg,Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, alloys includingthe above, or the like, and it is possible to use one type or acombination (for example, setting a laminate body having a plurality oflayers, mixed layers of a plurality of types, or the like) of two ormore types from the above.

In particular, in a case of using an alloy as the constituent materialof the cathode 11, it is preferable to use an alloy including stablemetal elements such as Ag, Al, and Cu, specifically, alloys of MgAg,AlLi, CuLi, and the like. By using the above alloys as the constituentmaterial of the cathode 11, it is possible to achieve an improvement inthe electron injection efficiency and stability properties of thecathode 11.

The average thickness of the cathode 11 is not particularly limited;however, approximately 100 to 10000 nm is preferable and approximately100 to 500 nm is more preferable.

Here, since the light emitting element 1 of the present embodiment is abottom emission type, there is no particular demand for lighttransmittance in the cathode 11. In addition, in a case of a topemission type, since there is a need to transmit light from the cathode11 side, the average thickness of the cathode 11 is preferablyapproximately 1 to 50 nm.

Hole Injection Layer

The hole injection layer 4 has a function of improving the holeinjection efficiency from the anode 3 (that is, a hole injectionproperty).

By providing the hole injection layer 4 between the anode 3 and the holetransporting layer 5 to be described later in this manner, the holetransporting property of the anode 3 is improved, and, as a result, itis possible to increase the light emitting efficiency of the lightemitting element 1.

This hole injection layer 4 includes material having a hole injectionproperty (that is, hole injection material).

The hole injection material included in the hole injection layer 4 isnot particularly limited; however, examples thereof include copperphthalocyanine,4,4′,4″-tris(N,N-phenyl-3-methyl-phenylamino)triphenylamine(m-MTDATA),N,N′-bis-(4-diphenylaminophenyl)-N,N′-diphenyl-biphenyl-4-4′-diamine,and the like.

Among the above, as the hole injection material included in the holeinjection layer 4, from the viewpoint of having an excellent holeinjection property and hole transporting property, it is preferable touse an amine based material, and diaminobenzene derivatives, benzidinederivatives (material having a benzidine skeleton), triamine basedcompounds having both a “diaminobenzene” unit and a “benzidine” unit inthe molecule, and tetraamine based compounds are more preferable.

The average thickness of the above hole injection layer 4 is notparticularly limited; however, approximately 5 to 90 nm is preferableand approximately 10 to 70 nm is more preferable.

Here, the hole injection layer 4 may be omitted according to theconstituent material of the anode 3 and the hole transporting layer 5.

Hole Transporting Layer

The hole transporting layer 5 has a function of transporting injectedholes from the anode 3 through the hole injection layer 4 to the carriertrapping layer 6 (that is, a hole transporting property).

The hole transporting layer 5 is configured to include a material (thatis, a hole transporting material) having a hole transporting property.

As the hole transporting material included in the hole transportinglayer 5, it is possible to use various P type polymer materials orvarious P type low-molecular-weight materials either singly or incombination and examples thereof include tetraarylbenzidine derivativessuch as N,N′-di(1-naphthyl)-N,N′-diphenyl-1,1′-diphenyl-4,4′-diamine(NPD), N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-diphenyl-4,4′-diamine(TPD), N,N,N′,N′-tetra-naphthyl-benzidine (TNB), and the like, andtetraaryldiaminofluorene compounds or derivatives thereof (amine basedmaterial), and it is possible to use one type or a combination of two ormore types from the above.

Among the above, as the hole transporting material included in the holetransporting layer 5, from the viewpoint of having an excellent holeinjection property and hole transporting property, it is preferable touse an amine based material, and benzidine derivatives (material havinga benzidine skeleton) are more preferable.

The average thickness of the above hole transporting layer 5 is notparticularly limited; however, approximately 5 to 90 nm is preferableand approximately 10 to 70 nm is more preferable.

Carrier Trapping Layer

In the present embodiment, the carrier trapping layer 6 is positionedbetween the red light emitting layer 7R and the hole transporting layer5, that is, further toward the anode 3 side than the red light emittinglayer 7R, and has a function of trapping electrons (carrier) comingthrough the red light emitting layer 7R and suppressing or preventingthe electrons from being injected to the hole transporting layer 5(anode 3) side.

The carrier trapping layer 6 has energy levels capable of trappingelectrons (carrier) coming through the red light emitting layer 7Rduring conduction between the anode 3 and the cathode 11, and the lightgenerated as a result at the time of returning to the ground state is inthe near infrared region. Accordingly, since it is possible toaccurately suppress or prevent alteration or degradation of theconstituent material of the hole transporting layer 5 and the holeinjection layer 4 caused by the injection of the electrons, alengthening of the life span of the light emitting element 1 isachieved. Furthermore, since the light emitted by the carrier trappinglayer 6 is in the near infrared region (infrared light) and is notcapable of being recognized by the human eye, it is possible to reliablyprevent the chromaticity of the visible light emitted by the lightemitting element 1 from changing.

In the invention, this carrier trapping layer 6 contains a thiazolebased compound represented by the following formula (1).

[In formula (1), A indicates a hydrogen atom, an alkyl group, an arylgroup which may have a substituent, an arylamino group, or a triarylamine, and B indicates a hydrogen atom, an alkyl group, an aryl groupwhich may have a substituent, an arylamino group, or a triaryl amine, ormay form a ring.]

With respect to the carrier trapping layer 6 configured by the abovematerial, since electrons coming through the red light emitting layer 7Rfrom the cathode 11 side are supplied (injected) along with the supply(injection) of holes from the anode 3 side, in the carrier trappinglayer 6, the holes and electrons are recombined, whereby the electrons(carrier) coming through the red light emitting layer 7R are trapped bythe carrier trapping layer 6. In addition, since excitons are generatedby the energy released during the recombination and energy (fluorescenceand phosphorescence) is released when the excitons return to the groundstate, the carrier trapping layer 6 emits infrared rays.

Here, the infrared rays emitted by the carrier trapping layer 6containing the thiazole based compound represented by theabove-described formula (1) are in the near infrared region, morespecifically, in the wavelength range of 700 nm or more to 1500 nm orless.

The luminescent light of such a long wavelength range is not capable ofbeing recognized by the human eye. Accordingly, in the light emittingelement 1, even if luminescent light of such a wavelength range isemitted, the recognized luminescent light becomes white light emittedfrom the three layers of the red light emitting layer 7R, blue lightemitting layer 7B, and the green light emitting layer 7G.

Accordingly, by selecting the layer emitting red light as the lightemitting layer provided for lengthening the life span of the lightemitting element 1 in this manner, the light emitting element 1 emitswhite light as luminescent light without changing the chromaticity.Accordingly, in a case of use as a white device, since there is no needto provide a color filter for extracting the desired luminescent lightin the light emitting element, it is possible to reliably prevent theelement configuration from becoming complicated and the number ofprocesses during the manufacturing of the light emitting element fromincreasing.

As the thiazole based compound represented by the above-describedformula (1), it is possible to classify the above-described group B intoI) a case showing a hydrogen atom, an alkyl group, an aryl group whichmay have a substituent, an arylamino group, or a triaryl amine, or II) acase of forming a ring, and, in the case of I), examples include thecompound represented by the following formula (1A) and, in the case ofII), examples include the compounds represented by the followingformulas (1B), (1C), and (1D).

First, description will be given of the case of I), that is, thecompound represented by the following formula (1A).

[In formula (1A), A and B each independently indicate a hydrogen atom,an alkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The above thiadiazole based compounds have energy levels capable oftrapping carriers, and the light generated as a result at the time ofreturning to the ground state is in the near infrared region.Accordingly, by configuring the above thiadiazole based compounds as atrapping material (light emitting material), the carrier trapping layer6 traps carriers and, along with this, emits light at a wavelength range(near infrared range) of 700 nm or more, that is, emits luminescentlight which is not recognizable to the human eye.

In particular, as the thiadiazole based compound used in the carriertrapping layer 6, the compounds represented by the following formula(2A) and formula (3A) are preferably used.

[In formulas (2A) and (3A), A each independently indicate a hydrogenatom, an alkyl group, an aryl group which may have a substituent, anarylamino group, or a triaryl amine.]

That is, in the formula (1A), B is preferably a phenyl group or a methylgroup, respectively.

The phenyl group and the methyl group respectively have comparativelyhigh chemical stability. Therefore, by using the above compound as atrapping material included in the carrier trapping layer 6, it ispossible to achieve a lengthening of the life span of the carriertrapping layer 6 and the light emitting element 1. In addition, since itis possible to suppress the molecular weight of the trapping material tobe comparatively small, it is possible to form the carrier trappinglayer 6 with high precision using vapor deposition. As a result, even inthis point, it is possible to achieve an increase in the efficiency anda lengthening of the life span of the light emitting element 1.

Furthermore, as the thiadiazole based compound used in the carriertrapping layer 6, the compounds represented by the following formulas(4A) to (9A) are preferably used, specifically, the compoundsrepresented by the following formulas D-1 to D-3 are particularlypreferably used.

[In formulas (4A) to (9A), R each independently indicates a hydrogenatom, an alkyl group, or an aryl group which may have a substituent. Inaddition, the carbon atoms of two adjacent Rs may be linked and have acyclic shape.]

Next, sequential description will be given of the case of II), that is,the compounds represented by the following formulas (1B) to (1D).

First, description will be given of the compounds represented by thefollowing formula (1B).

[In formula (1B), A each independently indicate a hydrogen atom, analkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The above thiadiazole based compounds have energy levels capable oftrapping carriers, and the light generated as a result at the time ofreturning to the ground state is in the near infrared region.Accordingly, by configuring the above thiadiazole based compounds as atrapping material (light emitting material), the carrier trapping layer6 traps carriers and, along with this, emits light at a wavelength range(near infrared range) of 700 nm or more, that is, emits luminescentlight which is not recognizable to the human eye.

In particular, as the thiadiazole based compound used in the carriertrapping layer 6, the compounds represented by the following formulas(2B) to (4B) are preferably used, specifically, for example, thecompounds represented by the following formulas D-4 to D-6 arepreferably used.

[In formulas (2B) to (4B), R's each independently indicate a hydrogenatom, an alkyl group, or an aryl group which may have a substituent. Inaddition, the carbon atoms of two adjacent Rs may be linked and have acyclic shape.]

Next, description will be given of the compound represented by thefollowing formula (1C).

[In formula (1C), A's each independently indicate a hydrogen atom, analkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The above thiadiazole based compounds have energy levels capable oftrapping carriers, and the light generated as a result at the time ofreturning to the ground state is in the near infrared region.Accordingly, by configuring the above thiadiazole based compounds as atrapping material (light emitting material), the carrier trapping layer6 traps carriers and, along with this, emits light at a wavelength range(near infrared range) of 700 nm or more, that is, emits luminescentlight which is not recognizable to the human eye.

In particular, as the thiadiazole based compound used in the carriertrapping layer 6, the compounds represented by the following formulas(2C) to (4C) are preferably used, specifically, the compoundsrepresented by the following formulas D-7 to D-9 are preferably used.

[In formulas (2C) to (4C), R's each independently indicate a hydrogenatom, an alkyl group, or an aryl group which may have a substituent. Inaddition, the carbon atoms of two adjacent Rs may be linked and have acyclic shape.]

Next, description will be given of the compound represented by thefollowing formula (1D).

[In formula (1D), A and B each independently indicate a hydrogen atom,an alkyl group, an aryl group which may have a substituent, an arylaminogroup, or a triaryl amine.]

The above thiadiazole based compounds have energy levels capable oftrapping carriers, and the light generated as a result at the time ofreturning to the ground state is in the near infrared region.Accordingly, by configuring the above thiadiazole based compounds as atrapping material (light emitting material), the carrier trapping layer6 traps carriers and, along with this, emits light at a wavelength range(near infrared range) of 700 nm or more, that is, emits luminescentlight which is not recognizable to the human eye.

In particular, as the thiadiazole based compound used in the carriertrapping layer 6, from the viewpoint of achieving an increase inefficiency and a lengthening of the life span, the compounds representedby the following formulas (2D) to (4D) are preferably used,specifically, the compounds represented by the following formulas D-10to D-12 are particularly preferably used.

[In formulas (2D) to (4D), R's each independently indicate a hydrogenatom, an alkyl group, or an aryl group which may have a substituent. Inaddition, the carbon atoms of two adjacent Rs may be linked and have acyclic shape.]

In addition, as the constituent material of the carrier trapping layer6, in addition to the above-described thiadiazole based compound(trapping material), a host material in which the thiadiazole basedcompound is added (supported) as a guest material (dopant) is preferablyused.

The host material generates excitons by recombining the holes andelectrons, and, along with this, has a function of transferring theenergy of the excitons in the light emitting material (Förster transferor Dexter transfer) and exciting the thiadiazole based compound.Therefore, it is possible to increase the carrier trapping efficiency ofthe thiadiazole based compound. For example, it is possible to use theabove host material after doping a light emitting material, which is aguest material, as a dopant in the host material.

The above host material is not particularly limited as long as theabove-described function is exhibited with respect to the thiadiazolebased compound to be used; however, examples thereof includedistyrylarylene derivatives, naphthacene derivatives (naphthacene basedmaterials), anthracene derivatives such as 2-t-butyl-9,10-di(2-naphthyl)anthracene (TBADN) (anthracene based material), perylene derivatives,distyryl benzene derivatives, bis(2-methyl-8-quinolinolato)(p-phenylphenolato)aluminium (BAlq), quinolinolate metal complexes suchas tris(8-quinolinolato)aluminium complex (Alq₃), amine derivatives(amine based material), oxadiazole derivatives, rubrene and derivativesthereof, silole derivatives, dicarbazole derivatives, oligothiophenederivatives, benzopyran derivatives, triazole derivatives, benzoxazolederivatives, benzothiazole derivatives, quinoline derivatives,4,4′-bis(2,2′-diphenylvinyl)biphenyl (DPVBi), carbazole derivatives suchas 3-phenyl-4-(1′-naphthyl)-5-phenyl-carbazole, 4,4′-N,N′-dicarbazolebiphenyl (CBP), and the like, and it is possible to use one type singlyor a combination of two or more types from the above.

Among the above, as the host material, in a case where the carriertrapping layer 6 is positioned between the red light emitting layer 7R(light emitting layer 7) and the anode 3 as in the present embodiment,it is preferable to use an acene based material or an amine basedmaterial.

The acene based material and the amine based material have littleunintended interaction with the thiadiazole based compound as describedabove. In addition, when using the above materials as the host material(in particular, anthracene based material, tetracene based material, andamine based materials), it is possible to transfer energy efficientlyfrom the host material to the thiadiazole based compound. This isconsidered to be due to the following: (a) that it is possible togenerate a singlet excitation state of the thiadiazole based compoundaccording to the energy transfer from the triplet excitation state ofthe host material, (b) that the overlap of the π electron cloud of thehost material and the electron cloud of the thiadiazole based compoundbecomes great, and (c) that the overlap of the fluorescence spectrum ofthe host material and the absorption spectrum of the thiadiazole basedcompound becomes great.

Due to the above, when using acene based material and amine basedmaterial as the host material, it is possible to increase the carriertrapping efficiency of the thiadiazole based compound.

In addition, the acene based material and the amine based material haveexcellent resistance with respect to electrons and holes. In addition,the acene based material and the amine based material are also excellentin thermal stability. Therefore, it is possible to achieve a lengtheningof the life span of the carrier trapping layer 6.

In addition, since the acene based material and the amine based materialhave an excellent hole transporting property, in a case where thecarrier trapping layer 6 is positioned between the red light emittinglayer 7R and the anode 3 as in the present embodiment, it is possible totransport the holes, which were not used in the light emitting of theinfrared light of the carrier trapping layer 6, to the red lightemitting layer 7R side, whereby it is possible to increase the lightemitting efficiency of the light emitting layer 7.

Here, in a case where naphthacene material is used as the host material,as in the present embodiment, it is preferable to adopt a configurationprovided with an intermediate layer 8. In this manner, it is possible toreliably prevent the light emitting efficiency of the visible lightemitting layer 7 from decreasing. Here, the acene material is notparticularly limited as long as it has an acene skeleton and exhibitsthe above-described effects and examples thereof include naphthalenederivatives, anthracene derivatives, naphthacene derivatives (tetracenederivatives), and pentacene derivatives, and, while it is possible touse one type or a combination of two or more types from the above, it ispreferable to use anthracene derivatives (anthracene based material) ortetracene derivatives (tetracene based material).

The tetracene based material is not particularly limited as long as ithas at least one tetracene skeleton in one molecule and is capable ofexhibiting the functions as the above-described host material; however,for example, the compound represented by the following formula IRH-1 ispreferably used, the compound represented by the following formula IRH-2is more preferably used, and the compound represented by the followingformula IRH-3 is even more preferably used.

[In the formula IRH-1, n indicates a natural number of 1 to 12, R'srepresent a substituent or a functional group and each independentlyindicate a hydrogen atom, an alkyl group, an aryl group which may have asubstituent, or an arylamino group. In addition, in the formulas IRH-2and IRH-3, R₁ to R₄ each independently indicates a hydrogen atom, analkyl group, an aryl group which may have a substituent, or an arylaminogroup. In addition, R₁ to R₄ may be the same or different from eachother.]

In addition, the tetracene based material is preferably configured bycarbon atoms and hydrogen atoms. In this manner, it is possible toprevent the generation of unintended interaction between the hostmaterial and the thiazole based compound. Accordingly, it is possible toincrease the carrier trapping efficiency by the thiadiazole basedcompound emitting infrared light. In addition, it is possible toincrease the resistance of the host material with respect to electronsand holes. Therefore, it is possible to achieve a lengthening of thelife span of the carrier trapping layer 6.

Specifically, as the tetracene based material, for example, it ispreferable to use the compound represented by the following formulasH1-1 to H1-11, and the compounds represented by the following formulasH1-12 to H1-27.

In addition, the anthracene based material is not particularly limitedas long as it has at least one anthracene skeleton in one molecule andis capable of exhibiting the functions as the above-described hostmaterial; however, for example, the compound represented by thefollowing formula IRH-4 or a derivative thereof is preferably used, andthe compounds represented by the following formulas IRH-5 to IRH-8 ismore preferably used.

[In the formula IRH-4, n indicates a natural number of 1 to 10, R'srepresent a substituent or a functional group and each independentlyindicate a hydrogen atom, an alkyl group, an aryl group which may have asubstituent, or an arylamino group. In addition, in the formulas IRH-5to IRH-8, R₁ and R₂ each independently indicates a hydrogen atom, analkyl group, an aryl group which may have a substituent, or an arylaminogroup. In addition, R₁ and R₂ may be the same or different from eachother.]

Further, the anthracene based material is preferably configured bycarbon atoms and hydrogen atoms. In this manner, it is possible toprevent the generation of unintended interaction between the hostmaterial and the thiazole based compound. Accordingly, it is possible toincrease the carrier trapping efficiency by the thiazole based compoundemitting infrared light. In addition, it is possible to increase theresistance of the host material with respect to electrons and holes.Therefore, it is possible to achieve a lengthening of the life span ofthe carrier trapping layer 6.

Specifically, as the anthracene based material, for example, thecompounds represented by the following formulas H2-1 to H2-16, thecompounds represented by the following formulas H2-17 to H2-36, and thecompounds represented by the following formulas H2-37 to H2-56.

Further, the amine based material is not particularly limited as long asit has an amine skeleton and exhibits the above-described effects and itis possible to use material having an amine skeleton from among the holetransporting materials described above; however, it is preferable to usea benzidine based amine derivative.

In particular, among benzidine based amine derivatives, ones in whichtwo or more naphthyl groups are injected are preferable. Examples of theabove benzidine based amine derivatives includeN,N′-bis(1-naphthyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (α-NPD)represented by the following chemical formula (22) ortetrakis-p-biphenylyl benzidine, N,N,N′,N′-tetra-naphthyl-benzidine(TNB) represented by the following chemical formula (23), or the like.

The content (doping amount) of the trapping material (thiazole basedcompound) in the carrier trapping layer 6 including the above trappingmaterial and host material is preferably 0.01 to 10 wt % and morepreferably 0.1 to 5 wt %. By setting the content of the trappingmaterial to be within the above range, it is possible to optimize thecarrier trap efficiency by emitting infrared light as luminescent light.

In addition, the average thickness of the carrier trapping layer 6 isnot particularly limited; however, approximately 1 to 60 nm ispreferable and approximately 3 to 50 nm is more preferable.

Red Light Emitting Layer

By conducting electricity between the above-described anode 3 andcathode 11, the red light emitting layer 7R emits red light asluminescent light (visible light).

The red light emitting layer 7R is configured by including red lightemitting material emitting red light.

The above red light emitting material is not particularly limited;however, it is possible to use one type or combine two or more types ofvarious types of red fluorescent material, or red phosphorescentmaterials.

The red fluorescent material is not particularly limited as long as itgenerates red fluorescent light and examples thereof include perylenederivatives, europium complexes, benzopyran derivatives, rhodaminederivatives, benzothioxanthene derivatives, porphyrin derivatives, nilered,2-(1,1-dimethylethyl)-6-(2-(2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H-benzo(ij)quinolizine-9-yl)ethenyl)-4H-pyran-4H-ylidene)propanedinitrile (DCJTB),4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM),and the like of compounds (diindenoperylene derivatives) represented bythe following chemical formula (17).

Among the above, diindenoperylene derivatives are preferably used as thered light emitting material. In this manner, it is possible to cause thered light emitting layer 7R to emit red light with a higher brightness.

The red phosphorescent material is not particularly limited as long asit generates red phosphorescence and examples thereof include metalcomplexes of iridium, ruthenium, platinum, osmium, rhenium, andpalladium, and further examples thereof include those in which at leastone in the ligands of the above metal complexes has a phenyl pyridineskeleton, a bipyridyl skeleton, a porphyrin skeleton, or the like. Morespecifically, examples thereof include tris(1-phenylisoquinoline)iridium, bis[2-(2′-benzo[4,5-α]thienyl) pyridinate-N, C³′]iridium(acetylacetonate) (btp2Ir(acac)),2,3,7,8,12,13,17,18-octaethyl-12H,23H-porphyrin-platinum (II),bis[2-(2′-benzo[4,5-a]thienyl) pyridinate-N,C³′]iridium, andbis(2-phenylpyridine) iridium (acetylacetonate).

In addition, as well as the above-described red light emittingmaterials, the red light emitting layer 7R preferably includes a hostmaterial in which a red light emitting material is set as the guestmaterial.

As the host material, it is possible to use materials similar to thosedescribed as host materials included in the carrier trapping layer 6.

Here, as in the present embodiment, in a case of a configuration wherethe carrier trapping layer 6 and the red light emitting layer 7R areadjacent and the carrier trapping layer 6 is positioned at the anode 3side, it is preferable that naphthacene based material be used as thehost material of the red light emitting layer 7R and that at least onetype from among naphthacene based material, anthracene based material,and amine based material be used as the host material of the carriertrapping layer 6. In this manner, since it is possible to reduce thedifference of the band gap between the carrier trapping layer 6 and thered light emitting layer 7R, it becomes possible to reduce the voltageincrease and emit red light with a further improved balance. That is,even if the carrier trapping layer 6 and the red light emitting layer 7Rare made to be adjacent, it is possible to emit red light with a furtherimproved balance and it is possible to trap the carriers coming throughthe red light emitting layer 7R in the carrier trapping layer 6.

Furthermore, in a case where anthracene based material is used as thehost material of the red light emitting layer 7R, it is preferable thatat least one type from among anthracene based material, and amine basedmaterial be used as the host material of the carrier trapping layer 6.In this manner, it is possible to obtain the same effect as above.

Intermediate Layer

The intermediate layer 8 is provided between the layers of the red lightemitting layer 7R and the blue light emitting layer 7B so as to be incontact therewith, and has a function of adjusting the movement of thecarrier (holes and electrons) between the red light emitting layer 7Rand the blue light emitting layer 7B. According to the above function,it is possible to cause the red light emitting layer 7R and the bluelight emitting layer 7B to emit light more efficiently, respectively.

The intermediate layer 8 may have any configuration as long as it has afunction of adjusting the movement of the carrier (holes and electrons);however, in particular, a configuration including the same type or thesame material as the host material of the above-described red lightemitting layer 7R and substantially not including material havingluminescence is preferable.

As the constituent material of the above intermediate layer 8, forexample, the same materials as described above as the host material ofthe carrier trapping layer 6 may be used, in particular, materialincluding acene based material may be suitably used.

By using such materials, the energy level of the highest occupiedmolecular orbital (HOMO) of the intermediate layer 8 are capable ofbeing set to be lower than the energy levels of the highest occupiedmolecular orbital (HOMO) of both the red light emitting layer 7R and theblue light emitting layer 7B and, furthermore, the energy level of thelowest unoccupied molecular orbital (LUMO) of the intermediate layer 8are capable of being set to be higher than the lowest unoccupiedmolecular orbital (LUMO) of both the red light emitting layer 7R and theblue light emitting layer 7B. As a result, the energy transfer of theexcitons between the red light emitting layer 7R and the blue lightemitting layer 7B is more reliably prevented.

The acene material is not particularly limited as long as it has anacene skeleton and exhibits the above-described effects and examplesthereof include naphthalene derivatives, anthracene derivatives,tetracene derivatives (naphthacene derivatives), pentacene derivatives,hexacene derivatives, heptacene derivatives, and the like, and, while itis possible to use one type or a combination of two or more types fromthe above, it is preferable to use tetracene (naphthacene) derivatives.

The tetracene (naphthacene) derivatives are not particularly limited;however, it is possible to use the same ones as the naphthacenederivatives described as the host material of the above-describedcarrier trapping layer 6.

The above tetracene (naphthacene) derivatives have a bipolar property.Accordingly, the intermediate layer 8 is capable of smoothlytransporting holes from the red light emitting layer 7R to the bluelight emitting layer 7B and, along with this, is capable of smoothlytransporting electrons from blue light emitting layer 7B to the redlight emitting layer 7R. In addition, the intermediate layer 8 hasexcellent resistance with respect to electrons and holes. Accordingly,the degradation of the intermediate layer 8 is prevented and it ispossible to improve the durability of the light emitting element 1 as aresult.

The content of the acene based material in the above intermediate layer8 is not particularly limited; however, 10 to 90 wt % is preferable, 30to 70 wt % is more preferable, and 40 to 60 wt % is even morepreferable.

As the constituent material of the intermediate layer 8, it isparticularly preferable to include an amine based material (aminederivative) as well as the above-described acene based material.

The amine based material (that is, the material having an amineskeleton) has an excellent hole transporting property, and the acenebased material (that is, the material having an acene skeleton)described above has an excellent electron transporting property incomparison with the amine based material. In this manner, theintermediate layer 8 has both an electron transporting property and ahole transporting property. That is, the intermediate layer 8 has abipolar property. When the intermediate layer 8 has a bipolar propertyin this manner, it is possible for holes to smoothly pass from the redlight emitting layer 7R through the intermediate layer 8 to the bluelight emitting layer 7B and, along with this, it is possible forelectrons to smoothly pass from the blue light emitting layer 7B throughthe intermediate layer 8 to the red light emitting layer 7R. As aresult, it is possible to efficiently inject electrons and holes intothe red light emitting layer 7R and the blue light emitting layer 7Brespectively, to thereby cause light to be emitted.

In addition, since the intermediate layer 8 above has a bipolarproperty, the resistance with respect to carriers (electrons, holes) isexcellent. Moreover, since the acene based material has excellentresistance with respect to excitons, even if the electrons and holesrecombine in the intermediate layer 8 and generate excitons, it ispossible to prevent or suppress the degradation of the intermediatelayer 8. In this manner, the degradation of the intermediate layer 8 dueto excitons is prevented or suppressed, and, as a result, it is possibleto achieve excellent durability in the light emitting element 1.

As the amine based material used in the above intermediate layer 8, itis possible to use the same material exemplified as the host material ofthe carrier trapping layer 6.

Here, the amine based material such asN,N′-bis(1-naphthyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (α-NPD)represented by the above-described chemical formula (22),N,N,N′,N′-tetra-naphthyl-benzidine (TNB) represented by theabove-described chemical formula (23), or the like, generally has anexcellent hole transporting property, and the degree of hole transfer ofthe amine based material is higher than the degree of hole transfer ofthe acene based material. Accordingly, it is possible for holes tosmoothly pass from the red light emitting layer 7R through theintermediate layer 8 to the blue light emitting layer 7B.

The content of the amine based material in the above intermediate layer8 is not particularly limited; however, 10 to 90 wt % is preferable, 30to 70 wt % is more preferable, and 40 to 60 wt % is even morepreferable.

In addition, the average thickness of the intermediate layer 8 is notparticularly limited; however, 1 to 100 nm is preferable, 3 to 50 nm ismore preferable, and 5 to 30 nm is even more preferable. In this manner,it is possible for the intermediate layer 8 to reliably adjust thetransfer of the holes and electrons between the red light emitting layer7R and the blue light emitting layer 7B while continuing to suppress thedriving voltage.

In contrast, when the average thickness of the intermediate layer 8exceeds the upper limit value, according to the constituent material orthe like of the intermediate layer 8, there are cases where the drivingvoltage is remarkably increased and the light emission (in particular,the white light emission) of the light emitting element 1 becomesdifficult. Meanwhile, when the average thickness of the intermediatelayer 8 is lower than the lower limit value, according to theconstituent material, driving voltage, and the like of the intermediatelayer 8, there is a concern that it may be difficult for theintermediate layer 8 to reliably adjust the transfer of the holes andelectrons between the red light emitting layer 7R and the blue lightemitting layer 7B.

Blue Light Emitting Layer

By conducting electricity between the above-described anode 3 andcathode 11, the blue light emitting layer 7B emits blue light asluminescent light (visible light).

The blue light emitting layer 7B is configured by including blue lightemitting material emitting blue light.

Examples of the above blue light emitting material include various typesof blue fluorescent material or blue phosphorescent material and it ispossible to use one type or combine two or more types thereof.

The blue fluorescent material is not particularly limited as long as itgenerates a blue fluorescence and examples thereof include styrylaminebased compound represented by the following chemical formula (24A) orthe following chemical formula (24B) such as styrylamine derivatives,fluoranthene derivatives, pyrene derivatives, perylene and perylenederivatives, anthracene derivatives, benzoxazole derivatives,benzothiazole derivatives, benzimidazole derivatives, chrysenederivatives, phenanthrene derivatives, distyrylbenzene derivatives,tetraphenylbutadiene, 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl(BCzVBi),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,5-dimethoxy-benzene-1,4-diyl)],poly[(9,9-oxydihexylfluorene-2,7-diyl)-ortho-co-(2-methoxy-5-{2-ethoxyhexyloxy}phenylene-1,4-diyl)],poly[(9,9-dioctylfluorene-2,7-diyl)-co-(ethyl benzene)], and the like.

The blue phosphorescent material is not particularly limited as long asit generates blue phosphorescence and examples thereof include metalcomplexes such as iridium, ruthenium, platinum, osmium, rhenium, andpalladium, specifically, bis[4,6-difluorophenyl pyridinate-N,C²′]-picolinate-iridium, tris[2-(2,4-difluorophenyl)pyridinate-N,C²′]iridium, bis[2-(3,5-trifluoromethyl)pyridinate-N,C²′]-picolinate-iridium, bis(4,6-difluorophenylpyridinate-N,C²′)-iridium (acetylacetonate), and the like.

In addition, as well as the above-described blue light emittingmaterials, the blue light emitting layer 7B preferably includes a hostmaterial in which a blue light emitting material is set as the guestmaterial.

As the host material, it is possible to use materials similar to thosedescribed as host materials included in the carrier trapping layer 6.

Green Light Emitting Layer

By conducting electricity between the above-described anode 3 andcathode 11, the green light emitting layer 7G emits green light asluminescent light (visible light).

The green light emitting layer 7G is configured by including green lightemitting material emitting green light.

The above green light emitting material is not particularly limited andit is possible to use one type or combine two or more types of varioustypes of green fluorescent material or green phosphorescent material.

The green fluorescent material is not particularly limited as long as itgenerates green fluorescence and examples thereof include coumarinderivatives, quinacridone and derivatives thereof such as thequinacridone derivatives and the like shown in the following chemicalformula (25), 9,10-bis[(9-ethyl-3-carbazole)-vinylenyle]-anthracene,poly(9,9-dihexyl-2,7-vinylenefluorolenylene),poly[(9,9-dioctylfluorene-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy}benzene)],poly[(9,9-dioctyl-2,7-divinylenefluorolenylene)-ortho-co-(2-methoxy-5-(2-ethoxylhexyloxy)-1,4-phenylene)],and the like.

The green phosphorescent material is not particularly limited as long asit generates green phosphorescence and examples thereof include metalcomplexes of iridium, ruthenium, platinum, osmium, rhenium, andpalladium, and, specifically, examples thereof includefac-tris(2-phenylpyridine) iridium (Ir(ppy)3), bis(2-phenylpyridinate-N,C²′) iridium (acetylacetonate),fac-tris[5-fluoro-2-(5-trifluoromethyl-2-pyridine)phenyl-C,N]iridium,and the like.

In addition, as well as the above-described green light emittingmaterials, the green light emitting layer 7G preferably includes a hostmaterial in which a green light emitting material is set as the guestmaterial.

As the host material, it is possible to use materials similar to thosedescribed as host materials included in the carrier trapping layer 6.

In addition, the host material of the above green light emitting layer7G preferably uses an acene derivative (acene based material) in thesame manner as the host material of the red light emitting layer 7R. Inthis manner, it is possible to cause the green light emitting layer 7Gto emit green light with higher brightness and higher efficiency.

Further, the host material of the green light emitting layer 7G ispreferably the same as the host material of the above-described bluelight emitting layer 7B. In this manner, since a band gap is notgenerated between the two light emitting layers 7G and 7B, it becomespossible to emit light with a good balance of green light and bluelight.

Electron Transporting Layer

The electron transporting layer 9 has a function of transportinginjected electrons from the cathode 11 through the electron injectionlayer 10 to the green light emitting layer 7G.

Examples of the constituent material (electron transporting material) ofthe electron transporting layer 9 include phenanthroline derivativessuch as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), quinolinederivative such as organic metal complexes in which 8-quinolinol such astris(8-quinolinolato)aluminium (Alq₃) and derivatives thereof are set asligand, azaindolizine derivatives, oxadiazole derivatives, perylenederivative, pyridine derivatives, pyrimidine derivatives, quinoxalinederivatives, diphenyl quinone derivatives, nitro-substituted fluorenederivatives, and the like, and it is possible to use one type or acombination of two or more types from the above.

Among the above, as the electron transporting material used in theelectron transporting layer 9, the use of azaindolizine derivatives ispreferable, in particular, the use of compounds (below, simply referredto as “azaindolizine based compounds”) having an azaindolizine skeletonand an anthracene skeleton in the molecule is more preferable.

In this manner, since a compound having an azaindolizine skeleton and ananthracene skeleton in the molecule is used as the electron transportingmaterial of the electron transporting layer 9 adjacent to the greenlight emitting layer 7G, it is possible to efficiently transport theelectrons from the electron transporting layer 9 to the green lightemitting layer 7G. Therefore, it is possible to give the light emittingelement 1 excellent light emitting efficiency.

In addition, since the electrons are efficiently transported from theelectron transporting layer 9 to the green light emitting layer 7G, itis possible to lower the voltage of the driving voltage of the lightemitting element 1 and, along with this, it is possible to achieve alengthening of the life span of the light emitting element 1.

Further, since the compound having an azaindolizine skeleton and ananthracene skeleton in the molecule has excellent stability (resistance)with respect to the electrons and holes, in this respect, it is possibleto achieve a lengthening of the life span of the light emitting element1.

For the electron transporting material (azaindolizine based compound)used in the electron transporting layer 9, the number of azaindolizineskeletons and anthracene skeletons included in one molecule ispreferably one or two, respectively. In this manner, it is possible forthe electron transporting property and electron injection property ofthe electron transporting layer 9 to be made to be excellent.

Specifically, as the azaindolizine based compound used in the electrontransporting layer 9, for example, it is preferable to use compoundsrepresented by the following formulas ELT-A1 to ELT-A24, compoundsrepresented by the following formulas ELT-B1 to ELT-B12, and compoundsrepresented by the following formulas ELT-C1 to ELT-C20.

The above azaindolizine compound has an excellent electron transportingproperty and an electron injection property. Therefore, it is possibleto improve the light emitting efficiency of the light emitting element1.

The fact that the electron transporting property and electron injectionproperty of the above azaindolizine compound are excellent is consideredto be for the following reasons.

Since the entire molecule of the azaindolizine based compound having anazaindolizine skeleton and an anthracene skeleton in the molecule asdescribed above is connected by the π-conjugated system, the electroncloud is spread over the entire molecule.

Thus, a portion of the azaindolizine skeleton of the above azaindolizinebased compound has a function of receiving electrons and a function ofsending out the received electrons to the portion of the anthraceneskeleton. On the other hand, a portion of the anthracene skeleton of theabove azaindolizine based compound has a function of receiving electronsfrom the portion of the azaindolizine skeleton and a function ofdelivering the received electrons to the layer adjacent to the anode 3side of the electron transporting layer 9, that is, the green lightemitting layer 7G.

Specifically, a portion of the azaindolizine skeleton of the aboveazaindolizine based compound has two nitrogen atoms, of which one (sidenear the portion of the anthracene skeleton) nitrogen atom has an sp2hybrid orbital and the other (side far from the portion of theanthracene skeleton) has an sp3 hybrid orbital. The nitrogen atom havingthe sp2 hybrid orbital configures a part of a conjugated system of amolecule of the azaindolizine based compound, and, along with this,functions as a portion receiving electrons since the electronegativityis higher than a carbon atom and the electron attraction force isstrong. Meanwhile, the nitrogen atom having the sp3 hybrid orbital isnot a normal conjugated system; however, since it has an unsharedelectron pair, it has a function as a portion in which the electrons aresent out toward the conjugated system of the molecule of theazaindolizine based compound.

On the other hand, since the portion of the anthracene skeleton of theabove azaindolizine based compound is electrically neutral, it ispossible to easily receive electrons from the portion of theazaindolizine skeleton. In addition, since the portion of the anthraceneskeleton of the above azaindolizine based compound has a large overlapbetween the constituent material of the green light emitting layer 7G,in particular, the host material (acene based material), and the orbit,it is possible to easily deliver electrons to the host material of thegreen light emitting layer 7G.

In addition, since the above azaindolizine based compound has anexcellent electron transporting property and an electron injectingproperty as described above, as a result, it is possible to lower thevoltage of the driving voltage of the light emitting element 1.

In addition, in the portion of the azaindolizine skeleton, the nitrogenatom having an sp2 hybrid orbital is stable even when reduced, and thenitrogen atom having an sp3 hybrid orbital is stable even when oxidized.Therefore, the above azaindolizine based compound has high stabilitywith respect to the electrons and the holes. As a result, it is possibleto achieve a lengthening of the life span of the light emitting element1.

In addition, in a case where two or more types from among the electrontransporting material described above are used in combination, theelectron transporting layer 9 may be configured by a mixed materialmixing two or more types of electron transporting material, and may beconfigured by laminating a plurality of layers configured by differentelectron transporting materials.

The average thickness of the electron transporting layer 9 is notparticularly limited; however, approximately 1.0 to 200 nm is preferableand 10 to 100 nm is more preferable.

Electron Injection Layer

The electron injection layer 10 has a function of improving the electroninjection efficiency from the cathode 11.

Examples of the constituent material (electron injection material) ofthe electron injection layer 10 include, for example, various types ofinorganic insulating material and various types of inorganicsemiconductor material.

Examples of the above inorganic insulating material include alkali metalchalcogenides (oxides, sulfides, selenides, tellurides), alkaline earthmetal chalcogenides, alkali metal halides and alkaline earth metalhalides, and the like, and it is possible to use one type or acombination of two or more types from the above. By configuring theelectron injection layer 10 with the above as the main material, it ispossible to further improve the electron injection property. Inparticular, alkali metal compounds (alkali metal chalcogenides, alkalimetal halides, and the like) have an extremely small work function, and,by using these to configure the electron injection layer 10, the lightemitting element 1 is able to obtain a high brightness.

Examples of the alkali metal chalcogenides include Li₂O, LiO, Na₂S,Na₂Se, NaO and the like.

Examples of the alkaline earth metal chalcogenides include CaO, BaO,SrO, BeO, BaS, MgO, CaSe, and the like.

Examples of the alkali metal halides include CsF, LiF, NaF, KF, LiCl,KCl, NaCl, and the like.

Examples of the alkaline earth metal halides include CaF₂, BaF₂, SrF₂,MgF₂, BeF₂, and the like. Examples of the inorganic semiconductormaterial include oxides including at least one element from among Li,Na, Ba, Ca, Sr, Yb, Al, Ga, In, Cd, Mg, Si, Ta, Sb, and Zn; nitrides oroxynitrides; and the like, and it is possible to use one type or acombination of two or more types from the above.

The average thickness of the electron injection layer 10 is notparticularly limited; however, approximately 0.1 to 1000 nm ispreferable, approximately 0.2 to 100 nm is more preferable, andapproximately 0.2 to 50 nm is even more preferable.

Here, the electron injection layer 10 may be omitted depending on theconstituent materials, thicknesses, and the like of the cathode 11 andthe electron transporting layer 9.

Sealing Member

The sealing member 12 is provided so as to cover the anode 3, thelaminate body 14, and the cathode 11, and has a function of hermeticallysealing the above and blocking oxygen and moisture. By providing thesealing member 12, it is possible to obtain an improvement in thereliability of the light emitting element 1 and effects such aspreventing alteration or degradation (improving the durability) thereof.

Examples of the constituent material of the sealing member 12 mayinclude Al, Au, Cr, Nb, Ta, or Ti, or an alloy including the above,silicon oxide, various types of resin materials, and the like. Here, ina case of using material having conductivity as a constituent materialof the sealing member 12, in order to prevent a short circuit, it ispreferable to provide an insulating film as necessary between thesealing member 12 and the anode 3, and the laminate body 14 and thecathode 11. In addition, the sealing member 12 is made to correspond tothe substrate 2 as a flat plate shape and may be sealed with sealingmaterial such as thermosetting resin, for example, therebetween.

According to the light emitting element 1 configured as described above,by providing the carrier trapping layer 6, it is possible to suppress orprevent the injection of electrons into the hole transporting layer 5and the hole injection layer 4 positioned at the anode 3 side relativeto the carrier trapping layer 6, and it is possible to accuratelysuppress or prevent alteration or degradation of the constituentmaterials of the above layers 4 and 5, whereby it is possible to attemptto lengthen the life span of the light emitting element 1. Furthermore,since the carrier trapping layer 6 contains the thiaazole based compoundrepresented by the above-described formula (1) as the trapping material,infrared light in a near infrared region which the human eye is notcapable of recognizing is emitted as luminescent light, whereby theluminescent light to be recognized is white light emitted from the threelayers of the red light emitting layer 7R, the blue light emitting layer7B, and the green light emitting layer 7G. Accordingly, in a case of useas a white device, since there is no need to provide a color filter forextracting the desired luminescent light in the light emitting device,it is possible to reliably prevent the device configuration frombecoming complicated and the number of processes during themanufacturing of the light emitting device from increasing.

It is possible to manufacture the above light emitting element 1 in thefollowing manner, for example.

[1] First, the substrate 2 is prepared, and the anode 3 is formed on thesubstrate 2.

It is possible to form the anode 3, for example, using chemical vapordeposition (CVD) such as thermal CVD, and plasma CVD, dry platingmethods such as vacuum deposition, wet plating methods such aselectrolytic plating, thermal spraying coating methods, sol-gel methods,MOD methods, metal foil bonding, or the like.

[2] Next, the hole injection layer 4 is formed on the anode 3.

For example, the hole injection layer 4 is preferably formed by a vaporphase process using a dry plating method such as a CVD method, vacuumdeposition, sputtering, or the like.

Here, for example, it is possible to form the hole injection layer 4 bysupplying material for forming the hole injection layer, in which a holeinjection material is dissolved in a solvent or dispersed in adispersion medium, onto the anode 3 and then performing drying (solventremoval or dispersion medium removal).

As the supply method of the material for forming the hole injectionlayer, it is possible to use, for example, various types of coatingmethod such as a spin coating method, a roll coating method, and an inkjet printing method. By using the above coating methods, it is possibleto form the hole injection layer 4 comparatively easily.

Examples of the solvent or dispersion medium used in the preparation ofthe material for forming the hole injection layer include various typesof inorganic solvents, various types of organic solvents, mixed solventsincluding the above, or the like. Here, for example, it is possible toperform the drying by leaving to stand at atmospheric pressure or in areduced pressure atmosphere, by a heating process, by the spraying ofinert gas, or the like.

In addition, prior to this step, oxygen plasma treatment may beperformed upon the upper surface of the anode 3. In this manner, it ispossible to impart a lyophilic property to the upper surface of theanode 3, remove (wash) organic matter attached to the upper surface ofthe anode 3, and adjust the work function in the vicinity of the uppersurface of the anode 3. Here, as the conditions of the oxygen plasmatreatment, for example, it is preferable to set a plasma power ofapproximately 100 to 800 W, an oxygen gas flow rate of approximately 50to 100 mL/min, a transport speed of the member to be treated (anode 3)of approximately 0.5 to 10 mm/sec, and a temperature of the substrate 2of approximately 70 to 90° C.

[3] Next, the hole transporting layer 5 is formed on the hole injectionlayer 4.

For example, the hole transporting layer 5 is preferably formed by avapor phase process using a dry plating method such as a CVD method,vacuum deposition, sputtering, or the like.

Here, for example, it is possible to perform the forming by supplyingmaterial for forming the hole transporting layer, in which a holetransporting material is dissolved in a solvent or dispersed in adispersion medium, onto the hole injection layer 4 and then performingdrying (solvent removal or dispersion medium removal).

[4] Next, the carrier trapping layer 6 is formed on the holetransporting layer 5.

It is possible to form the carrier trapping layer 6 by a vapor phaseprocess using a dry plating method such as vacuum deposition, forexample.

[5] Next, the red light emitting layer 7R is formed on the carriertrapping layer 6.

It is possible to form the red light emitting layer 7R, for example, bya vapor phase process using a dry plating method such as a CVD method,vacuum deposition, sputtering, or the like.

[6] Next, the intermediate layer 8 is formed on the red light emittinglayer 7R.

It is possible to form the intermediate layer 8, for example, by a vaporphase process using a dry plating method such as a CVD method, vacuumdeposition, sputtering, or the like.

In addition, it is possible to form the intermediate layer 8 bysupplying material for forming the intermediate layer, in which theconstituent material thereof is dissolved in a solvent or dispersed in adispersion medium, onto the red light emitting layer 7R and thenperforming drying (solvent removal or dispersion medium removal).

[7] Next, a blue light emitting layer 7B is formed on the intermediatelayer 8.

It is possible to form the blue light emitting layer 7B, for example, bya vapor phase process using a CVD method, vacuum deposition, a dryplating method such as sputtering, or the like.

[8] Next, the green light emitting layer 7G is formed on the blue lightemitting layer 7B.

It is possible to form the green light emitting layer 7G, for example,by a vapor phase process using a CVD method, vacuum deposition, a dryplating method such as sputtering, or the like.

[9] Next, the electron transporting layer 9 is formed on the green lightemitting layer 7G.

It is possible to form the electron transporting layer 9, for example,by a vapor phase process using a CVD method, vacuum deposition, a dryplating method such as sputtering, or the like.

In addition, it is possible to form the electron transporting layer 9 bysupplying material for forming the electron transporting layer, in whichelectron transporting material is dissolved in a solvent or dispersed ina dispersion medium, onto the green light emitting layer 7G and thenperforming drying (solvent removal or dispersion medium removal).

[10] Next, the electron injection layer 10 is formed on the electrontransporting layer 9.

In a case where inorganic material is used as the constituent materialof the electron injection layer 10, it is possible to form the electroninjection layer 10, for example, by using a vapor phase process using aCVD method, vacuum deposition, a dry plating method such as sputtering,or the like, coating and firing ink having inorganic fine particles, orthe like.

[11] Next, the cathode 11 is formed on the electron injection layer 10.

It is possible to form the cathode 11, for example, using a vacuumdeposition method, a sputtering method, metal foil bonding, coating andfiring ink having metal fine particles, or the like.

Through the steps described above, it is possible to obtain the lightemitting element 1.

Finally, the sealing member 12 is used as a cover so as to cover theobtained light emitting element 1 and bonded to the substrate 2.

Second Embodiment

FIG. 2 is a cross-sectional view schematically showing the secondembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of thesecond embodiment centering on the differences with the above-describedfirst embodiment, and description of similar matters will be omitted.

Apart from the fact that the light emitting element 1 of the secondembodiment omits the forming of the red light emitting layer 7R, theblue light emitting layer 7B, and the green light emitting layer 7G aslight emitting layers emitting visible light, and forms a yellow lightemitting layer 7Y, and a cyan light emitting layer 7C, the lightemitting element is the same as the light emitting element of the firstembodiment.

That is, in the light emitting element 1 shown in FIG. 2, an anode 3, ahole injection layer 4, a hole transporting layer 5, a carrier trappinglayer 6, an intermediate layer 8, a yellow light emitting layer 7Y, acyan light emitting layer 7C, an electron transporting layer 9, anelectron injection layer 10, and a cathode 11 are laminated in thisorder. In other words, in the light emitting element 1, between theanode 3 and the cathode 11, from the anode 3 side to the cathode 11side, a laminate body 14, in which the hole injection layer 4, the holetransporting layer 5, the carrier trapping layer 6, the intermediatelayer 8, the yellow light emitting layer 7Y, the cyan light emittinglayer 7C, the electron transporting layer 9, and the electron injectionlayer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to each lightemitting layer of the yellow light emitting layer 7Y and the cyan lightemitting layer 7C, electrons are supplied (injected) from the cathode 11side and, along with this, holes are supplied (injected) from the anode3 side. Thus, in each light emitting layer, the holes and the electronsare recombined, excitons are generated by the energy released during therecombination, and energy (fluorescence and phosphorescence) is releasedwhen the excitons return to the ground state. Therefore, the yellowlight emitting layer 7Y and the cyan light emitting layer 7Crespectively emit yellow and cyan visible light. In this manner, thelight emitting element 1 of the present embodiment emits white visiblelight. Here, in the present embodiment, the visible light emitting layer7 emitting visible light is configured by the two layers of the yellowlight emitting layer 7Y and the cyan light emitting layer 7C.

In addition, in the present embodiment, the carrier trapping layer 6 ispositioned on the anode 3 side relative to the visible light emittinglayer 7 and is provided between the intermediate layer 8 and the holetransporting layer 5. In this manner, the electrons coming through theintermediate layer 8 are injected into the hole transporting layer 5,whereby it is possible to accurately suppress or prevent the alterationor degradation of the constituent material of the hole transportinglayer 5 and the hole injection layer 4, and, as a result, it is possibleto achieve a lengthening of the life span of the light emitting element1.

In addition, as luminescent light, the carrier trapping layer 6 emitsinfrared light in a near infrared range which is not capable of beingrecognized by the human eye. Therefore, the luminescent light to berecognized is white light emitted from the two layers of the yellowlight emitting layer 7Y and the cyan light emitting layer 7C. Therefore,in a case of use as a white device, since there is no need to provide acolor filter for extracting the desired luminescent light in the lightemitting element, it is possible to reliably prevent the deviceconfiguration from becoming complicated and the number of processesduring the manufacturing of the light emitting element from increasing.

As in the present embodiment, the light emitting element according to anaspect of the invention is capable of being suitably applied to aconfiguration in which the visible light emitting layer 7 is configuredof two layers and which is provided with yellow light emitting layer 7Yemitting a yellow luminescent color as visible light.

Yellow Light Emitting Layer

By conducting electricity between the anode 3 and the cathode 11, theyellow light emitting layer 7Y emits yellow light as luminescent light(visible light).

The above yellow light emitting layer 7Y is configured by including ayellow light emitting material emitting yellow light.

The above yellow light emitting material is not particularly limited,and various types of yellow fluorescent material and yellowphosphorescent material are capable of being used singly or in acombination of two types or more.

The yellow fluorescent material is not particularly limited as long asit generates yellow fluorescence, examples thereof include tetracenebased compounds represented by the following chemical formula (26A) andtetraphenyl naphthacene (known as rubrene), and it is possible to useone type or a combination of two or more types from the above.

In addition, yellow phosphorescent material is not particularly limitedas long as it generates yellow phosphorescence, and examples thereofinclude tris(2-phenyl quinoline)iridium (III) represented by thefollowing formula (26B), and the like.

Cyan Light Emitting Layer

By conducting electricity between the anode 3 and the cathode 11, thecyan light emitting layer 7C emits cyan light as luminescent light(visible light).

The above cyan light emitting layer 7C is configured by including a cyanlight emitting material emitting cyan light.

The above cyan light emitting material is not particularly limited andit is possible to use various types of cyan fluorescent materials andcyan phosphorescent material singly or in a combination of two or more.

The cyan fluorescent material is not particularly limited as long as itgenerates cyan fluorescence, and examples thereof include styrylaminederivatives such as the styrylamine based compound shown by the chemicalformula (24A), 4,4′-bisdiphenylaminodistilbene, and the like, and it ispossible to use one type or a combination of two or more types from theabove.

In addition, the cyan phosphorescent material is not particularlylimited as long as it generates cyan phosphorescence, and examplesthereof includebis(3,5-difluoro-2-(2-pyridyl)phenyl)-(2-carboxypyridyl)iridium (III),and the like represented by the following formula (27).

Furthermore, it is preferable that, in addition to the above-describedyellow light emitting material and the cyan light emitting material,host materials in which the yellow light emitting material and the cyanlight emitting material are set as guest materials be included in theyellow light emitting layer 7Y and the cyan light emitting layer 7C,respectively.

Here, as the host material, it is possible to use materials similar tothose described as host materials included in the carrier trapping layer6.

Third Embodiment

FIG. 3 is a cross-sectional view schematically showing the thirdembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of thethird embodiment centering on the differences with the above-describedfirst embodiment, and description of similar matters will be omitted.

Apart from the fact that the light emitting element 1 of the thirdembodiment omits the forming of the red light emitting layer 7R, and thegreen light emitting layer 7G as light emitting layers emitting visiblelight, and forms an independent blue light emitting layer 7B, the lightemitting element is the same as the light emitting element of the firstembodiment.

That is, in the light emitting element 1 shown in FIG. 3, an anode 3, ahole injection layer 4, a hole transporting layer 5, a carrier trappinglayer 6, an intermediate layer 8, a blue light emitting layer 7B, anelectron transporting layer 9, an electron injection layer 10, and acathode 11 are laminated in this order. In other words, in the lightemitting element 1, between the anode 3 and the cathode 11, from theanode 3 side to the cathode 11 side, a laminate body 14, in which thehole injection layer 4, the hole transporting layer 5, the carriertrapping layer 6, the intermediate layer 8, the blue light emittinglayer 7B, the electron transporting layer 9, and the electron injectionlayer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to the blue lightemitting layer 7B, electrons are supplied (injected) from the cathode 11side and, along with this, holes are supplied (injected) from the anode3 side. Thus, in the blue light emitting layer 7B, the holes and theelectrons are recombined, excitons are generated by the energy releasedduring the recombination, and energy (fluorescence and phosphorescence)is released when the excitons return to the ground state. Therefore, theblue light emitting layer 7B emits blue visible light. That is, thelight emitting element 1 of the present embodiment emits blue visiblelight. Accordingly, in the present embodiment, the visible lightemitting layer 7 emitting visible light is configured by the one layerof the blue light emitting layer 7B.

In addition, in the present embodiment, the carrier trapping layer 6 ispositioned at the anode 3 side relative to the blue light emitting layer7B and is provided between the intermediate layer 8 and the holetransporting layer 5. In this manner, the electrons (carrier) comingthrough the intermediate layer 8 are injected into the hole transportinglayer 5, whereby it is possible to accurately suppress or prevent thealteration or degradation of the constituent material of the holetransporting layer 5 and the hole injection layer 4, and, as a result,it is possible to achieve a lengthening of the life span of the lightemitting element 1.

In addition, as luminescent light, the carrier trapping layer 6 emitsinfrared light in a near infrared range which is not capable of beingrecognized by the human eye. Therefore, the luminescent light to berecognized is blue light emitted from the one layer of the blue lightemitting layer 7B. Therefore, in comparison with the light emittingelement configured by combining light emitting layers generating redlight as in the past, since there is no need to provide a color filterfor extracting the desired luminescent light in the light emittingelement, it is possible to reliably prevent the element configurationfrom becoming complicated and the number of processes during themanufacturing of the light emitting element from increasing.

In addition, in the present embodiment, since the light emitting element1 includes an intermediate layer 8 between the carrier trapping layer 6and the blue light emitting layer 7B, it is possible to adjust thetransfer of holes and electrons between the carrier trapping layer 6 andthe blue light emitting layer 7B, whereby it is possible to preventenergy transfer of the excitons between the carrier trapping layer 6 andthe blue light emitting layer 7B. As a result, the blue light emittinglayer 7B emits light with good balance, and the light emitting element 1emits blue light as visible light with greater reliability. In addition,the carrier coming through the intermediate layer 8 is trapped by thecarrier trapping layer 6. Here, it is possible to obtain such an effecteven more remarkably in a case where the blue light emitting layer 7Bcontains blue phosphorescent material as the light emitting material.That is, by preventing the energy transfer of the excitons between thecarrier trapping layer 6 and the blue light emitting layer 7B, it ispossible to reliably prevent deactivation of triplet excitons generatedin the blue phosphorescent material.

Here, as in the present embodiment, in a case where the carrier trappinglayer 6 is positioned at the anode 3 side relative to the blue lightemitting layer 7B, by adopting a configuration using anthracene basedmaterial as the host material of the blue light emitting layer 7B andusing at least one type from among anthracene based material and aminebased material as the host material of the carrier trapping layer 6, itis possible to omit the forming of the intermediate layer 8 between thecarrier trapping layer 6 and the blue light emitting layer 7B. Byrespectively configuring the carrier trapping layer 6 and the blue lightemitting layer 7B with the above-described materials, it is possible toreduce the difference of the band gap between the carrier trapping layer6 and the blue light emitting layer 7B. Therefore, even when the formingof the intermediate layer 8 is omitted, the voltage increase caused bythe contact of the carrier trapping layer 6 and the blue light emittinglayer 7B is reduced and it is possible to emit the blue light with goodbalance. That is, even if the carrier trapping layer 6 and the bluelight emitting layer 7B are made to be adjacent, it is possible to emitthe blue light with good balance, and it is possible to trap the carriercoming through the blue light emitting layer 7B in the carrier trappinglayer 6.

In addition, as in the present embodiment, when the visible lightemitting layer 7 is configured of one layer and the light emittingelement 1 is provided with a light emitting layer emitting blue (shortwavelength) luminescent light as in the blue light emitting layer 7B, byapplying the light emitting element of the invention, it is possible tomore reliably achieve a lengthening of the life span of the blue lightemitting layer 7B which is a light emitting layer having a short lifespan. Therefore, when the light emitting element 1 is provided with alight emitting layer emitting blue luminescent light as in the bluelight emitting layer 7B, the light emitting element according to anaspect of the invention may be suitably applied.

In addition, as in the present embodiment, in a case where the carriertrapping layer 6 is provided at the anode 3 side relative to the bluelight emitting layer 7B, the intermediate layer 8 is preferably providedbetween the carrier trapping layer 6 and the blue light emitting layer7B. In this manner, even in a case where one in which the LUMO (lowestunoccupied molecular orbital) relationship of the host material includedin each layer is larger in the blue light emitting layer 7B is selected,since it is possible to accurately suppress or prevent the collection ofthe electrons in the blue light emitting layer 7B from being reduced, itis possible to cause the blue light emitting layer 7B to reliably emitblue light.

Fourth Embodiment

FIG. 4 is a cross-sectional view schematically showing a fourthembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of thefourth embodiment centering on the differences with the above-describedthird embodiment, and description of similar matters will be omitted.

The light emitting element 1 of the fourth embodiment is the same as thelight emitting element of the third embodiment other than the fact that,as the light emitting layer emitting visible light, a yellow lightemitting layer 7Y is independently formed instead of the blue lightemitting layer 7B.

That is, in the light emitting element 1 shown in FIG. 4, an anode 3, ahole injection layer 4, a hole transporting layer 5, a carrier trappinglayer 6, an intermediate layer 8, a yellow light emitting layer 7Y, anelectron transporting layer 9, an electron injection layer 10, and acathode 11 are laminated in this order. In other words, in the lightemitting element 1, between the anode 3 and the cathode 11, from theanode 3 side to the cathode 11 side, a laminate body 14, in which thehole injection layer 4, the hole transporting layer 5, the carriertrapping layer 6, the intermediate layer 8, the yellow light emittinglayer 7Y, the electron transporting layer 9, and the electron injectionlayer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to the yellow lightemitting layer 7Y, electrons are supplied (injected) from the cathode 11side and, along with this, holes are supplied (injected) from the anode3 side. Thus, in the yellow light emitting layer 7Y, the holes and theelectrons are recombined, excitons are generated by the energy releasedduring the recombination, and energy (fluorescence and phosphorescence)is released when the excitons return to the ground state. Therefore, theyellow light emitting layer 7Y emits yellow visible light. That is, thelight emitting element 1 of the present embodiment emits yellow visiblelight. Accordingly, in the present embodiment, the visible lightemitting layer 7 emitting visible light is configured by the one layerof the yellow light emitting layer 7Y.

As in the present embodiment, when the visible light emitting layer 7 isconfigured of one layer and the light emitting element 1 is providedwith a light emitting layer emitting yellow (short wavelength)luminescent light as in the yellow light emitting layer 7Y, by applyingthe light emitting element of the invention, it is possible to morereliably achieve a lengthening of the life span of the yellow lightemitting layer 7Y which is a light emitting layer having a short lifespan. Therefore, when the light emitting element 1 is provided with alight emitting layer emitting yellow luminescent light as in the yellowlight emitting layer 7Y, the light emitting element according to anaspect of the invention may be suitably applied.

Fifth Embodiment

FIG. 5 is a cross-sectional view schematically showing a fifthembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of thefifth embodiment centering on the differences with the above-describedfirst embodiment, and description of similar matters will be omitted.

The light emitting element 1 of the fifth embodiment is the same as thelight emitting element of the third embodiment other than the fact thatthe laminating position of the carrier trapping layer 6 is different andthe forming of the intermediate layer 8 is omitted.

That is, in the light emitting element 1 shown in FIG. 5, an anode 3, ahole injection layer 4, a hole transporting layer 5, a blue lightemitting layer 7B, a carrier trapping layer 6, an electron transportinglayer 9, an electron injection layer 10, and a cathode 11 are laminatedin this order. In other words, in the light emitting element 1, betweenthe anode 3 and the cathode 11, from the anode 3 side to the cathode 11side, a laminate body 14, in which the hole injection layer 4, the holetransporting layer 5, the blue light emitting layer 7B, the carriertrapping layer 6, the electron transporting layer 9, and the electroninjection layer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, similarly to the light emittingelement 1 of the third embodiment, with respect to the blue lightemitting layer 7B, electrons are supplied (injected) from the cathode 11side and, along with this, holes are supplied (injected) from the anode3 side. Thus, in the blue light emitting layer 7B, the holes and theelectrons are recombined, excitons are generated by the energy releasedduring the recombination, and energy (fluorescence and phosphorescence)is released when the excitons return to the ground state. Therefore, theblue light emitting layer 7B emits blue visible light. That is, thelight emitting element 1 of the present embodiment emits blue visiblelight. Accordingly, in the present embodiment, the visible lightemitting layer 7 emitting visible light is configured by the one layerof the blue light emitting layer 7B.

In addition, by conducting electricity between the anode 3 and thecathode 11, the carrier trapping layer 6 emits infrared light asluminescent light (visible light).

It is possible to configure the carrier trapping layer 6 in the samemanner as the carrier trapping layer 6 provided in the light emittingelement 1 of the above-described first embodiment; however, as in thepresent embodiment, in a case where the carrier trapping layer 6 ispositioned at the cathode 11 side relative to the blue light emittinglayer 7B, it is preferable to use an acene based material or aquinolinolate based metal complex as the host material included in thecarrier trapping layer 6. Since the above materials are excellent inelectron transportability and excellent in resistance to electrons andholes, it is possible to achieve a lengthening of the life span whileproviding the carrier trapping layer 6 with a function as an electrontransporting layer.

Here, the quinolinolate based metal complex is not particularly limited;however, examples thereof include bis(2-methyl-8-quinolinolato)(p-phenylphenolate)aluminium (BAlq), tris(8-quinolinolato)aluminium complex(Alq₃), or the like, and it is possible to use one type or a combinationof two or more types from the above.

In addition, the carrier trapping layer 6 is provided so as to bepositioned between the blue light emitting layer 7B and the electrontransporting layer 9 at the cathode 11 side relative to the blue lightemitting layer 7B. In this manner, holes (carrier) coming through theblue light emitting layer 7B are injected into the electron transportinglayer 9 whereby it is possible to accurately suppress or prevent thealteration or degradation of the constituent material of the electrontransporting layer 9 and the electron injection layer 10, and, as aresult, it is possible to achieve a lengthening of the life span of thelight emitting element 1.

In addition, as luminescent light, the carrier trapping layer 6 emitsinfrared light in a near infrared range which is not capable of beingrecognized by the human eye. Therefore, the luminescent light to berecognized is blue light emitted from the one layer of the blue lightemitting layer 7B. Therefore, since there is no need to provide a colorfilter for extracting the desired luminescent light in the lightemitting element as in the past, it is possible to reliably prevent theelement configuration from becoming complicated and the number ofprocesses during the manufacturing of the light emitting element fromincreasing.

In addition, in a case where an anthracene based material is used as thehost material, as in the present embodiment, the application is morepreferable in a case where the carrier trapping layer 6 is positioned atthe cathode 11 side relative to the blue light emitting layer 7B. Forexample, in a case where the host of the blue light emitting layer 7B isan anthracene based compound, the light emitting efficiency is increasedby providing a hole transporting layer or the like configured by an arylamine based material at the anode 3 side, forming a collection of thecarrier in the vicinity of the interface thereof, and causing the bluelight emitting layer 7B to emit light. However, if a configuration isadopted in which a carrier trapping layer 6 configured by an anthracenebased compound is further provided between the blue light emitting layer7B and the hole transporting layer, it is easier to collect the carrierin the carrier trapping layer 6. For the above reason, the carriertrapping layer 6 is preferably arranged at the cathode 11 side relativeto the blue light emitting layer 7B.

Sixth Embodiment

FIG. 6 is a cross-sectional view schematically showing a sixthembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of thesixth embodiment centering on the differences with the above-describedfirst embodiment, and description of similar matters will be omitted.

In the sixth embodiment, the layer configuration thereof is the same asthat of the light emitting element of the first embodiment other thanthe fact that a light emitting element 1 provided with a carriergenerating layer 15 is set to be applied.

That is, in the light emitting element 1 shown in FIG. 6, an anode 3, ahole injection layer 4, a hole transporting layer 5, a red lightemitting layer 7R, an electron transporting layer 9, an electroninjection layer 10, a carrier generating layer 15, a hole transportinglayer 5′, a carrier trapping layer 6, an intermediate layer 8, a bluelight emitting layer 7B, a green light emitting layer 7G, an electrontransporting layer 9′, an electron injection layer 10′, and a cathode 11are laminated in this order. In other words, in the light emittingelement 1, between the anode 3 and the cathode 11, from the anode 3 sideto the cathode 11 side, a laminate body 14, in which the hole injectionlayer 4, the hole transporting layer 5, the red light emitting layer 7R,the electron transporting layer 9, the electron injection layer 10, thecarrier generating layer 15, the hole transporting layer 5′, the carriertrapping layer 6, the intermediate layer 8, the blue light emittinglayer 7B, the green light emitting layer 7G the electron transportinglayer 9′, and the electron injection layer 10′, are laminated in thisorder, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to each layer of thered light emitting layer 7R, the blue light emitting layer 7B, and thegreen light emitting layer 7G, electrons are supplied (injected) fromthe cathode 11 side and, along with this, holes are supplied (injected)from the anode 3 side. Thus, in each light emitting layer, the holes andthe electrons are recombined, excitons are generated by the energyreleased during the recombination, and energy (fluorescence andphosphorescence) is released when the excitons return to the groundstate. Therefore, the red light emitting layer 7R, the blue lightemitting layer 7B, and the green light emitting layer 7G respectivelyemit red, blue, and green visible light. In this manner, the lightemitting element 1 of the present embodiment emits white visible light.Here, in the present embodiment, the visible light emitting layer 7emitting visible light is configured by the three layers of the redlight emitting layer 7R, the blue light emitting layer 7B, and the greenlight emitting layer 7G.

In addition, in the present embodiment, the carrier trapping layer 6 ispositioned at the anode 3 side relative to the blue light emitting layer7B and the green light emitting layer 7G and is provided between theintermediate layer 8 and the hole transporting layer 5′. In this manner,the electrons (carrier) coming through the intermediate layer 8 areinjected into the hole transporting layer 5′ side, whereby it ispossible to accurately suppress or prevent the alteration or degradationof the constituent material of the hole transporting layer 5′ and thecarrier generating layer 15, and, as a result, it is possible to achievea lengthening of the life span of the light emitting element 1.

In addition, as luminescent light, the carrier trapping layer 6 emitsinfrared light in a near infrared range which is not capable of beingrecognized by the human eye. Therefore, the luminescent light to berecognized is white light emitted from the three layers of the red lightemitting layer 7R, the blue light emitting layer 7B, and the green lightemitting layer 7G. Therefore, in a case of use as a white device, sincethere is no need to provide a color filter for extracting the desiredluminescent light in the light emitting element, it is possible toreliably prevent the element configuration from becoming complicated andthe number of processes during the manufacturing of the light emittingelement from increasing.

In addition, in the light emitting element 1 of the present embodiment,since holes and electrons are generated in the carrier generating layer15, and, among these, the electrons are injected into the red lightemitting layer 7R and the holes are injected into the blue lightemitting layer 7B and the green light emitting layer 7G, it is possibleto cause the light emitting element 1 to emit light with a greaterbrightness, whereby it is possible to obtain a light emitting element 1with excellent light emitting efficiency.

Carrier Generating Layer

The carrier generating layer 15 includes an organic cyan compound (belowreferred to as “an aromatic ring-containing organic cyan compound”)having an aromatic ring.

The aromatic ring-containing organic cyan compound has an excellentelectron attraction property. Therefore, the aromatic ring-containingorganic cyan compound is capable of taking out electrons from the holetransporting material included in the hole transporting layer 5′ incontact therewith. As a result, even if a voltage is not applied to thecarrier generating layer 15, in the vicinity of the interface betweenthe carrier generating layer 15 and the hole transporting layer 5′,electrons are generated at the carrier generating layer 15 side and theholes are generated at the hole transporting layer 5′ side. In such astate, when a driving voltage is applied between the anode 3 and thecathode 11, that is, a voltage is applied to the carrier generatinglayer 15, holes generated in the vicinity of the interface between thecarrier generating layer 15 and the hole transporting layer 5′ aretransported by the driving voltage and contribute to the light emissionof the blue light emitting layer 7B and the green light emitting layer7G. In addition, the electrons generated in the vicinity of theinterface between the carrier generating layer 15 and the holetransporting layer 5′ are transported by the driving voltage andcontribute to the light emission of the red light emitting layer 7R andthe green light emitting layer 7G.

Thus, the generation of the holes and electrons in the carriergenerating layer 15 is continuously performed while the driving voltageis applied and the above holes and electrons respectively contribute tothe light emission of the blue light emitting layer 7B, the red lightemitting layer 7R, and the green light emitting layer 7G.

In addition, since the aromatic ring-containing organic cyan compound isorganic material, in comparison with a case where the carrier generatinglayer is configured of metal oxide, since it is possible to reliablyprevent the metal oxide from contacting the hole transporting material(organic material) included in the hole transporting layer 5′, thealteration or degradation of the hole transporting material may beprevented.

In addition, as well as being a comparatively stable compound, thearomatic ring-containing organic cyan compound is a compound capable ofeasily forming the carrier generating layer 15 using a vapor phase filmformation method such as vapor deposition. For this reason, theinvention is capable of being suitably used in the manufacturing of thelight emitting element 1, whereby not only does the quality of themanufactured light emitting element 1 become more easily stabilized, butthe yield of the light emitting element 1 also becomes high.

The above aromatic ring-containing organic cyan compound is notparticularly limited; however, examples thereof includehexaazatriphenylene derivatives into which a cyano group has beenintroduced, in particular, the use of the hexaazatriphenylenederivatives as shown in the following chemical formula (40) is morepreferable.

In the above-described chemical formula (40), R1 to R6 are eachindependently a cyano group (—CN), a sulfonic group (—SO₂R′), asulfoxide group (—SOR′), a sulfonamide group (—SO₂NR′₂), a sulfonategroup (—SO₃R′), a nitro group (—NO₂), or a trifluoromethane (—CF₃)group, and at least one substituent among R1 to R6 is a cyano group. Inaddition, R′ is an amine group, an amide group, an ether group, or analkyl group which is substituted with an ester group or unsubstitutedand which has 1 to 60 carbon atoms, an aryl group, or a heterocyclicgroup.

Such compounds have an excellent function as an aromatic ring-containingorganic cyan compound, that is, an electron attraction property, wherebyit is possible to more reliably take out electrons from the adjacenthole transporting layer 5′ and it is possible to more reliably transportthe taken out electrons to the electron injection layer 10 (anode 3)side.

In addition, as the aromatic ring-containing organic cyan compound, itis more preferable that, in the compounds shown in chemical formula (40)as described above, R1 to R6 be all cyano groups. That is, as thearomatic ring-containing organic cyan compound, the use ofhexacyanohexaazatriphenylene as shown in the following chemical formula(50) is preferable. By having a plurality of cyano groups having a highelectron extracting property in this manner, the compound shown in thefollowing formula (50) may exhibit the above-described functions moreremarkably.

In addition, the aromatic ring-containing organic cyan compound ispreferably present in an amorphous state in the carrier generating layer15. In this manner, it is possible to obtain a more remarkable effect ofthe aromatic ring-containing organic cyan compound described above.Here, by forming the carrier generating layer 15 using a vapor phasefilm formation method such as a vacuum deposition method, it is possibleto set the aromatic ring-containing organic cyan compound to anamorphous state.

In addition, the average thickness of the carrier generating layer 15 isnot particularly limited; however, approximately 5 nm or more to 40 nmor less is preferable, and approximately 10 nm or more to 30 nm or lessis more preferable. In this manner, it is possible to reliably exhibitthe functions of the carrier generating layer 15 while preventing thedriving voltage of the light emitting element 1 from becoming high.

Here, as the constituent materials of the hole transporting layer 5′,the electron transporting layer 9′, and the electron injection layer10′, it is possible to use the examples given for the constituentmaterials of the hole transporting layer 5, the electron transportinglayer 9, and the electron injection layer 10, and the constituentmaterials configuring each corresponding layer may be the same ordifferent, respectively.

Seventh Embodiment

FIG. 7 is a cross-sectional view schematically showing a seventhembodiment of the light emitting element according to an aspect of theinvention.

Below, description will be given of the light emitting element of theseventh embodiment centering on the differences with the above-describedthird embodiment, and description of similar matters will be omitted.

The light emitting element 1 of the seventh embodiment is the same asthe light emitting element of the third embodiment other than the factthat the forming of the hole transporting layer 5 having a function oftransporting holes is omitted and the carrier trapping layer 6 is madeto have both a function as the hole transporting layer 5 and a functionas the carrier trapping layer 6.

That is, in the light emitting element 1 shown in FIG. 7, an anode 3, ahole injection layer 4, a carrier trapping layer 6, an intermediatelayer 8, a blue light emitting layer 7B, an electron transporting layer9, an electron injection layer 10, and a cathode 11 are laminated inthis order. In other words, in the light emitting element 1, between theanode 3 and the cathode 11, from the anode 3 side to the cathode 11side, a laminate body 14, in which the hole injection layer 4, thecarrier trapping layer 6, the intermediate layer 8, the blue lightemitting layer 7B, the electron transporting layer 9, and the electroninjection layer 10 are laminated in this order, is interposed.

Thus, the entirety of the light emitting element 1 is provided on thesubstrate 2 and is also sealed with a sealing member 12.

In the above light emitting element 1, with respect to the blue lightemitting layer 7B, electrons are supplied (injected) from the cathode 11side and, along with this, holes are supplied (injected) from the anode3 side. Thus, in the blue light emitting layer 7B, the holes and theelectrons are recombined, excitons are generated by the energy releasedduring the recombination, and energy (fluorescence and phosphorescence)is released when the excitons return to the ground state. Therefore, theblue light emitting layer 7B emits blue visible light. That is, thelight emitting element 1 of the present embodiment emits blue visiblelight. Accordingly, in the present embodiment, the visible lightemitting layer 7 emitting visible light is configured by the one layerof the blue light emitting layer 7B.

In addition, it is possible to realize the configuring of the carriertrapping layer 6 to have both of the function as a hole transportinglayer 5 and the function as a carrier trapping layer 6 by doping(adding) a thiazole based compound represented by the above-describedformula (1) to the constituent material (hole transporting material) ofthe hole transporting layer 5, which was exemplified in the firstembodiment. Furthermore, in such a case, as the hole transportingmaterial, the use of an amine based material is particularly preferable.In this manner, it becomes possible to allow more remarkable exhibitionof both functions.

Next, description will be given of a light emitting device (lightemitting device according to an aspect of the invention) provided withthe light emitting element according to an aspect of the inventiondescribed above.

Illumination Light Source

First, description will be given of a case where the light emittingdevice according to an aspect of the invention is applied to anillumination light source. FIG. 8A to 8B are views showing an embodimentof an illumination light source applying the light emitting deviceaccording to an aspect of the invention.

The illumination light source 200 shown in FIG. 8A to 8B is a lightsource used for illumination, in particular, illuminating the inside ofa room.

The illumination light source 200 includes a transparent substrate 205and a light emitting element 1.

The light emitting element 1 includes a transparent electrode 202, acounter electrode 203, and a laminate body 201, and, by applying anelectric field between the transparent electrode 202 and the counterelectrode 203, the light emitting layers provided in the laminate body201 are made to emit light. Thus, for example, the inside of a room maybe illuminated by luminescent light generated in the light emittinglayer passing through the transparent substrate 205.

In the present embodiment, the light emitting element 1 provided in theillumination light source 200 emits infrared light of a near infraredregion which is not capable of being recognized by the human eye andvisible light.

Accordingly, by configuring the illumination light source 200 to beprovided with the light emitting elements described in each embodimentas the light emitting element 1, it is possible to use the illuminationlight source 200 as a light source emitting various colors ofluminescent light.

In addition, since the illumination light source 200 is provided withthe light emitting element 1 having a long life span without changingthe chromaticity, the reliability thereof is excellent.

Light Emitting Device

Next, description will be given of a case where the light emittingdevice according to an aspect of the invention is applied to a displayapparatus.

FIG. 9 is a longitudinal cross-sectional view showing an embodiment of adisplay apparatus in which the light emitting device according to anaspect of the invention is applied.

The display apparatus 100 shown in FIG. 9 includes a substrate 2, aplurality of light emitting elements 1A, and a plurality of drivingtransistors 24 for respectively driving each light emitting element 1A.Here, the display apparatus 100 is a display panel having a top emissionstructure.

A plurality of driving transistors 24 are provided on the substrate 2and a planarization layer 22 configured of an insulating material isformed so as to cover the above driving transistors 24.

Each driving transistor 24 includes a semiconductor layer 241 formed ofsilicon, a gate insulating layer 242 formed on the semiconductor layer241, a gate electrode 243 formed on the gate insulating layer 242, asource electrode 244, and a drain electrode 245.

On the planarization layer, light emitting elements 1A are provided tocorrespond to each driving transistor 24.

On the planarization layer 22 in the light emitting element 1A, areflective film 32, an anti-corrosion film 33, the anode 3, a laminatebody 14A, the cathode 11, and a cathode cover 34 are laminated in thisorder. In the present embodiment, the anodes 3 of each light emittingelement 1A configure pixel electrodes, and are electrically connected tothe drain electrodes 245 of each driving transistor 24 by conductiveunits (wiring) 27. In addition, the cathode 11 of each light emittingelement 1A is set as a common electrode.

Among the light emitting elements 1A in FIG. 9, respectively, the lightemitting element 1R emits red light as visible light, the light emittingelement 1G emits green light as visible light, and the light emittingelement 1B emits blue light as visible light.

Among the above light emitting elements 1A, a light emitting element 1emitting infrared light which is not capable of being recognized by thehuman eye in addition to the visible light is applied in the lightemitting element 1B. That is, the light emitting element 1 described inthe third embodiment, the fifth embodiment, and the seventh embodimentis applied to the light emitting element 1B.

Partition walls 31 are provided between adjacent light emitting elements1A. In addition, an epoxy layer 35 configured of epoxy resin is formedso as to cover the above. Then, on the epoxy layer 35, the sealingsubstrate 20 is provided so as to cover them.

Since a light emitting element 1A having a long life span is providedwithout changing the chromaticity, the above display apparatus 100 hasexcellent reliability.

Such a display apparatus 100 is capable of being incorporated intovarious types of electronic apparatuses.

Electronic Apparatus

FIG. 10 is a perspective view showing a configuration of a mobile type(or a notebook type) personal computer in which the electronic apparatusaccording to an aspect of the invention is applied.

In the drawing, a personal computer 1100 is configured by a main bodyunit 1104 provided with a keyboard 1102, and a display unit 1106provided with a display section 1000, and the display unit 1106 isrotatably supported through a hinge structure unit with respect to themain body unit 1104.

In the personal computer 1100, the above-described display apparatus 100is applied to the display section 1000.

Since a light emitting element 1 having high efficiency and a long lifespan is provided, the above personal computer 1100 has excellentreliability.

Here, in addition to the personal computer of FIG. 10 (mobile typepersonal computer), the electronic apparatus according to an aspect ofthe invention is capable of being applied to mobile phones, digitalstill cameras, televisions, video cameras, viewfinder type and monitordirect-view type video tape recorders, laptop personal computers, carnavigation systems, pagers, electronic organizers (including those withcommunication function), electronic dictionaries, calculators,electronic game machines, word processors, workstations, videophones,television monitors for security, electronic binoculars, electronicthermometers, POS terminals, apparatuses provided with touch screen (forexample, cash dispensers of financial institutions, automatic ticketvending machines), medical equipment (for example, electronicthermometers, sphygmomanometers, blood glucose meters, pulse measuringdevices, pulse wave measuring devices, ECG display devices, ultrasonicdiagnostic devices, and display devices for endoscopes), fishfinders,various types of measurement apparatuses, meters (for example,instruments for vehicles, aircraft, and ships), flight simulators,various other types of monitor, projection-type display devices such asprojectors, or the like.

Above, description has been given of the light emitting element, lightemitting device, and electronic apparatus according to an aspect of theinvention based on the embodiments of the drawings; however, theinvention is not limited thereto.

For example, it is possible to substitute the light emitting element,light emitting device, and electronic apparatus according to an aspectof the invention with arbitrary replacements capable of exhibitingsimilar functions, or to add arbitrary configurations thereto.

For example, in the light emitting element according to an aspect of theinvention, two or more arbitrary configurations shown in the first toseventh embodiments may be combined.

EXAMPLES

Next, description will be given of specific examples according to anaspect of the invention.

1. Manufacturing of Thiazole Based Compound Synthesis Example A1Synthesis of Compound Represented by the Above-Described Formula D-2

Synthesis (A1-1)

1500 ml of fuming nitric acid was put into a 5 liter flask and cooled.1500 ml of sulfuric acid was added separately while preserving thetemperature at 10 to 50° C. Further, 150 g of compound (a) which isdibromo benzothiadiazole which is a raw material was added thereto insmall amounts over 1 hour. At that time, the solution temperature wasset to be 5° C. or less. After addition of the total amount, a reactionwas caused for 20 hours at room temperature (25° C.). After thereaction, the reaction solution was poured into 3 kg of ice and wasstirred overnight. Thereafter, the resultant was filtered, and washedwith methanol and heptane.

After heating and dissolving the remaining material after the filteringin 200 ml of toluene, filtering was performed after cooling to roomtemperature, the remaining material was washed with a small amount oftoluene, and dried under reduced pressure.

In this manner, 60 g of a compound (b)(4,7-dibromo-5,6-dinitrobenzo[1,2,5]thiadiazole) having an HPLC purityof 95% was obtained.

Synthesis (A1-2)

Under an argon atmosphere, 30 g of compound (b) which is the obtaineddibromo body, 54.2 g of a boronic acid body of triphenylamine, 2500 mlof toluene, and a 2M cesium carbonate aqueous solution (152 g/(distilledwater) 234 ml) were put into a 5 liter flask, and reaction was performedovernight at 90° C. After the reaction, the resultant was filtered,separated, and concentrated, 52 g of the obtained coarse solid wereseparated using silica gel columns (SiO₂ 5 kg), and a red-purple solidwas obtained.

In this manner, 8.9 g of a compound (c) having an HPLC purity of 96% wasobtained.

Here, during the synthesis of the boronic acid body of triphenylamine,under an argon atmosphere, 246 g of 4-bromotriphenylamine (commercialproduct) and 1500 ml of dehydrated tetrahydrofuran were put into a 5liter flask, and 570 ml of a 1.6M n-BuLi/hexane solution was addeddropwise over 3 hours at −60° C. After 30 minutes, 429 g of boric acidtriisopropyl was added dropwise over 1 hour. After the dropping,reaction was performed overnight without modifying the temperature.After the reaction, 2 liters of water were added dropwise thereto,followed by extraction and separation with 2 liters of toluene. Anorganic layer was concentrated, recrystallized, filtered, and dried,whereby 160 g of a white boronic acid body which was the desired productwas obtained.

The HPLC purity of the obtained boronic acid body was 99%.

Synthesis (A1-3)

Under an argon atmosphere, 8 g of the obtained compound (c), which is adinitro body, 7 g of reduced iron, and 600 ml of acetic acid were put ina 1 liter flask, reacted for 4 hours at 80° C., and cooled to roomtemperature. After the reaction, the reaction solution was poured into1.5 liters of ion exchanged water, and 1.5 liters of ethyl acetate werefurther added thereto. After the addition, since the solid wasprecipitated, 1 liter of tetrahydrofuran and 300 g of salt were addedthereto and separation was performed. An aqueous layer was re-extractedwith 1 liter of tetrahydrofuran. The concentrated and dried resultantwas again washed with a small amount of water and methanol, and anorange solid was obtained.

In this manner, 7 g of the compound (d) having an HPLC purity of 80%were obtained.

Synthesis (A1-4)

Under an argon atmosphere, 4.5 g of the obtained compound (d), which isa diamine body, 3.7 g of benzyl, and 300 ml of acetic acid as a solventwere put into a 1 liter flask, and reaction was performed for 2 hours at80° C. After the reaction, cooling was performed to room temperature,and the reaction solution was poured into 1 liter of ion exchangedwater, the crystals were filtered, washed, and 7 g of a black-greensolid were obtained. Then, the black-green solid was purified using asilica gel column (SiO₂ 1 kg).

In this manner, 4 g of compound (e) (compound represented by the formulaD-2) having an HPLC purity of 99% were obtained. The result of massspectrometry of the compound (e) was M+: 826.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A2 Synthesis of Compound Represented by the FormulaD-1

Synthesis (A2-1) to (A2-3)

In the synthesis (A1-2) described in the synthesis example A1, compound(d), which is a diamine body, was obtained in the same manner assynthesis (A1-1) to (A1-3) other than the fact that phenylboronic acidwas used instead of the boronic acid body of triphenylamine.

Synthesis (A2-4)

Under an argon atmosphere, 2.3 g of the obtained compound (d), which isa diamine body, 3.7 g of benzyl, and 300 ml of acetic acid as a solventwere put into a 1 liter flask, and reaction was performed for 2 hours at80° C. After the reaction, cooling was performed to room temperature,and the reaction solution was poured into 1 liter of ion exchangedwater, the crystals were filtered, washed, and 7 g of a black-greensolid were obtained. Then, the black-green solid was purified using asilica gel column (SiO₂ 1 kg).

In this manner, 2.7 g of compound (e) (compound represented by theformula D-1) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 492.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A3 Synthesis of Compound Represented by the FormulaD-11

Synthesis (A3-1) to (A3-3)

Similarly to the synthesis (A1-1) to (A1-3) described above by synthesisexample A1, compound (d), which is a diamine body, was obtained.

Synthesis (A3-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 0.6 g of 9,10-phenanthrenequinone, and 300 ml of aceticacid as a solvent were put into a 1 liter flask, and reaction wasperformed for 2 hours at 80° C. After the reaction, cooling wasperformed to room temperature, and the reaction solution was poured into1 liter of ion exchanged water, the crystals were filtered, washed, and2 g of a black-green solid were obtained. Then, the black-green solidwas purified using a silica gel column (SiO₂ 1 kg).

In this manner, 1.5 g of compound (e) (compound represented by theformula D-11) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 824.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A4 Synthesis of Compound Represented by the FormulaD-10

Synthesis (A4-1) to (A4-3)

In the synthesis (A1-2) described in the synthesis example A1, compound(d), which is a diamine body, was obtained in the same manner assynthesis (A1-1) to (A1-3) other than the fact that phenylboronic acidwas used instead of the boronic acid body of triphenylamine.

Synthesis (A4-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 2.4 g of 9,10-phenanthrenequinone, and 300 ml of aceticacid as a solvent were put into a 1 liter flask, and reaction wasperformed for 2 hours at 80° C. After the reaction, cooling wasperformed to room temperature, and the reaction solution was poured into1 liter of ion exchanged water, the crystals were filtered, washed, and2 g of a black-green solid were obtained. Then, the black-green solidwas purified using a silica gel column (SiO₂ 1 kg).

In this manner, 1.8 g of compound (e) (compound represented by theformula D-10) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 490.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A5 Synthesis of Compounds Represented by the FormulaD-5

Synthesis (A5-1) to (A5-3)

Compound (d), which is a diamine body, was obtained in the same manneras synthesis (A1-1) to (A1-3) described in the synthesis example A1.

Synthesis (A5-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 5.7 ml (1 mol/L) of o-benzoquinone solution (VoigtGlobal Distribution Inc.), and 300 ml of acetic acid as a solvent wereput into a 1 liter flask, and reaction was performed for 2 hours at 80°C. After the reaction, cooling was performed to room temperature, andthe reaction solution was poured into 1 liter of ion exchanged water,the crystals were filtered, washed, and 2 g of a black-green solid wereobtained. Then, the black-green solid was purified using a silica gelcolumn (SiO₂ 1 kg).

In this manner, 0.8 g of compound (e) (compound represented by theformula D-5) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 724.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A6 Synthesis of Compound Represented by the FormulaD-4

Synthesis (A6-1) to (A6-3)

In the synthesis (A1-2) described in the synthesis example A1, compound(d), which is a diamine body, was obtained in the same manner assynthesis (A1-1) to (A1-3) other than the fact that phenylboronic acidwas used instead of the boronic acid body of triphenylamine.

Synthesis (A6-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 12 ml (1 mol/L) of o-benzoquinone aqueous solution(Voigt Global Distribution Inc.), and 300 ml of acetic acid as a solventwere put into a 1 liter flask, and reaction was performed for 2 hours at80° C. After the reaction, cooling was performed to room temperature,and the reaction solution was poured into 1 liter of ion exchangedwater, the crystals were filtered, washed, and 2 g of a black-greensolid were obtained. Then, the black-green solid was purified using asilica gel column (SiO₂ 1 kg).

In this manner, 0.9 g of compound (e) (compound represented by theformula D-4) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 390.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A7 Synthesis of Compound Represented by the FormulaD-8

Synthesis (A7-1) to (A7-3)

The compound (d), which is a diamine body, was obtained in the samemanner as synthesis (A1-1) to (A1-3) described in the synthesis exampleA1.

Synthesis (A7-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 0.9 g of 1,2-naphthoquinone, and 300 ml of acetic acidas a solvent were put into a 1 liter flask, and reaction was performedfor 2 hours at 80° C. After the reaction, cooling was performed to roomtemperature, and the reaction solution was poured into 1 liter of ionexchanged water, the crystals were filtered, washed, and 2 g of ablack-green solid were obtained. Then, the black-green solid waspurified using a silica gel column (SiO₂ 1 kg).

In this manner, 1.4 g of compound (e) (compound represented by theformula D-8) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 774.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

Synthesis Example A8 Synthesis of Compound Represented by the FormulaD-7

Synthesis (A8-1) to (A8-3)

In the synthesis (A1-2) described in the synthesis example A1, compound(d), which is a diamine body, was obtained in the same manner assynthesis (A1-1) to (A1-3) other than the fact that phenylboronic acidwas used instead of the boronic acid body of triphenylamine.

Synthesis (A8-4)

Under an argon atmosphere, 1.5 g of the obtained compound (d), which isa diamine body, 1.9 g of 1,2-naphthoquinone, and 300 ml of acetic acidas a solvent were put into a 1 liter flask, and reaction was performedfor 2 hours at 80° C. After the reaction, cooling was performed to roomtemperature, and the reaction solution was poured into 1 liter of ionexchanged water, the crystals were filtered, washed, and 2 g of ablack-green solid were obtained. Then, the black-green solid waspurified using a silica gel column (SiO₂ 1 kg).

In this manner, 1.4 g of compound (e) (compound represented by theformula D-7) having an HPLC purity of 99% were obtained. The result ofmass spectrometry of the compound (e) was M+: 440.

Furthermore, the obtained compound (e) was purified by sublimation at aset temperature of 340° C. After the sublimation purification, the HPLCpurity of the compound (e) was 99%.

2. Manufacturing of Light Emitting Element Example 1

<1> First, a transparent glass substrate having an average thickness of0.5 mm was prepared. Next, an ITO electrode (anode) having an averagethickness of 100 nm was formed on this substrate using a sputteringmethod.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 40 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-1 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<4> Next, on the carrier trapping layer, an intermediate layer having anaverage thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<5> Next, on the intermediate layer, a blue light emitting layer havingan average thickness of 30 nm was formed by using the vacuum depositionmethod to vapor deposit the constituent materials of the blue lightemitting layer. As the constituent materials of the blue light emittinglayer, a compound (styrylamine based compound) represented by thechemical formula (24B) was used as the light emitting material (guestmaterial), and a compound (anthracene based material) represented by theformula H2-30 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in theblue light emitting layer was set to 6.0 wt %.

<6> Next, an electron transporting layer having an average thickness of40 nm was formed on the blue light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<7> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<8> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<9> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 2

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-4 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 3

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-7 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 4

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-10 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 5

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-2 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 6

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-5 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 7

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-8 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 8

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-11 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1.

Example 9

A light emitting element was manufactured in the same manner as Example1 other than that a compound represented by the formula D-11 was used asthe thiadiazole based compound of the carrier trapping layer in step 3of Example 1, instead of the compound represented by the formula D-1 andthat the adding of the host material was omitted and an intermediatelayer was formed in step 4 of Example 1.

Comparative Example 1

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 60 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe blue light emitting layer was vapor deposited with a vacuumdeposition method to form a blue light emitting layer having an averagethickness of 30 nm. As the constituent materials of the blue lightemitting layer, a compound (styrylamine based compound) represented bythe chemical formula (24B) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the blue light emitting layer was set to 6.0 wt %.

<4> Next, an electron transporting layer having an average thickness of40 nm was formed on the blue light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<5> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<6> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<7> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 10

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 40 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<4> Next, on the carrier trapping layer, an intermediate layer having anaverage thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<5> Next, on the intermediate layer, a yellow light emitting layerhaving an average thickness of 30 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of theyellow light emitting layer. As the constituent materials of the yellowlight emitting layer, a compound (tetracene based compound) representedby the chemical formula (26A) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the yellow light emitting layer was set to 3.0 wt %.

<6> Next, an electron transporting layer having an average thickness of40 nm was formed on the yellow light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<7> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<8> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<9> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Comparative Example 2

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 60 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe yellow light emitting layer was vapor deposited with a vacuumdeposition method to form a yellow light emitting layer having anaverage thickness of 30 nm. As the constituent materials of the yellowlight emitting layer, a compound (tetracene based compound) representedby the chemical formula (26A) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the yellow light emitting layer was set to 3.0 wt %.

<4> Next, an electron transporting layer having an average thickness of40 nm was formed on the yellow light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<5> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<6> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<7> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 11

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 35 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<4> Next, on the carrier trapping layer, an intermediate layer having anaverage thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<5> Next, on the intermediate layer, a yellow light emitting layerhaving an average thickness of 20 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of theyellow light emitting layer. As the constituent materials of the yellowlight emitting layer, a compound (tetracene based compound) representedby the chemical formula (26A) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the yellow light emitting layer was set to 3.0 wt %.

<6> Next, on the yellow light emitting layer, a cyan light emittinglayer having an average thickness of 20 nm was formed by using thevacuum deposition method to vapor deposit the constituent materials ofthe cyan light emitting layer. As the constituent materials of the cyanlight emitting layer, a compound (styrylamine based compound)represented by the chemical formula (24B) was used as the light emittingmaterial (guest material), and a compound (anthracene based material)represented by the formula H2-30 was used as the host material. Inaddition, the content (doping concentration) of the light emittingmaterial (dopant) in the cyan light emitting layer was set to 6.0 wt %.

<7> Next, an electron transporting layer having an average thickness of25 nm was formed on the cyan light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<8> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<9> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<10> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Comparative Example 3

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 55 nm.

<3> Next, on the hole transporting layer, a yellow light emitting layerhaving an average thickness of 20 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of theyellow light emitting layer. As the constituent materials of the yellowlight emitting layer, a compound (tetracene based compound) representedby the chemical formula (26A) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the yellow light emitting layer was set to 3.0 wt %.

<4> Next, on the yellow light emitting layer, a cyan light emittinglayer having an average thickness of 20 nm was formed by using thevacuum deposition method to vapor deposit the constituent materials ofthe cyan light emitting layer. As the constituent materials of the cyanlight emitting layer, a compound (styrylamine based compound)represented by the chemical formula (24B) was used as the light emittingmaterial (guest material), and a compound (anthracene based material)represented by the formula H2-30 was used as the host material. Inaddition, the content (doping concentration) of the light emittingmaterial (dopant) in the cyan light emitting layer was set to 6.0 wt %.

<5> Next, an electron transporting layer having an average thickness of25 nm was formed on the cyan light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<6> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<7> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<8> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 12

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 30 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<4> Next, on the carrier trapping layer, a red light emitting layerhaving an average thickness of 15 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of the redlight emitting layer. As the constituent materials of the red lightemitting layer, a compound (diindenoperylene derivative) represented bythe chemical formula (17) was used as the light emitting material (guestmaterial), and a compound (tetracene based material) represented by theformula H1-5 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in thered light emitting layer was set to 2.0 wt %.

<5> Next, on the red light emitting layer, an intermediate layer havingan average thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<6> Next, on the intermediate layer, a blue light emitting layer havingan average thickness of 20 nm was formed by using the vacuum depositionmethod to vapor deposit the constituent materials of the blue lightemitting layer. As the constituent materials of the blue light emittinglayer, a compound (styrylamine based compound) represented by thechemical formula (24B) was used as the light emitting material (guestmaterial), and a compound (anthracene based material) represented by theformula H2-30 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in theblue light emitting layer was set to 5.0 wt %.

<7> Next, on the blue light emitting layer, a green light emitting layerhaving an average thickness of 20 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of thegreen light emitting layer. As the constituent materials of the greenlight emitting layer, a compound (quinacridone derivative) representedby the chemical formula (25) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the green light emitting layer was set to 6.0 wt %.

<8> Next, an electron transporting layer having an average thickness of25 nm was formed on the green light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<9> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<10> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<11> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Comparative Example 4

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 35 nm.

<3> Next, on the hole transporting layer, a red light emitting layerhaving an average thickness of 15 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of the redlight emitting layer. As the constituent materials of the red lightemitting layer, a compound (diindenoperylene derivative) represented bythe chemical formula (17) was used as the light emitting material (guestmaterial), and a compound (tetracene based material) represented by theformula H1-5 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in thered light emitting layer was set to 2.0 wt %.

<4> Next, on the red light emitting layer, an intermediate layer havingan average thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<5> Next, on the intermediate layer, a blue light emitting layer havingan average thickness of 20 nm was formed by using the vacuum depositionmethod to vapor deposit the constituent materials of the blue lightemitting layer. As the constituent materials of the blue light emittinglayer, a compound (styrylamine based compound) represented by thechemical formula (24B) was used as the light emitting material (guestmaterial), and a compound (anthracene based material) represented by theformula H2-30 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in theblue light emitting layer was set to 5.0 wt %.

<6> Next, on the blue light emitting layer, a green light emitting layerhaving an average thickness of 20 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of thegreen light emitting layer. As the constituent materials of the greenlight emitting layer, a compound (quinacridone derivative) representedby the chemical formula (25) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the green light emitting layer was set to 6.0 wt %.

<7> Next, an electron transporting layer having an average thickness of25 nm was formed on the green light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<8> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<9> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<10> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 13

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 60 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe blue light emitting layer was vapor deposited with a vacuumdeposition method to form a blue light emitting layer having an averagethickness of 30 nm. As the constituent materials of the blue lightemitting layer, a compound (styrylamine based compound) represented bythe chemical formula (24B) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the blue light emitting layer was set to 6.0 wt %.

<4> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (anthracene basedmaterial) represented by the formula H2-30 was used as the hostmaterial. In addition, the content (doping concentration) of thethiadiazole based compound (dopant) in the carrier trapping layer wasset to 3.0 wt %.

<5> Next, an electron transporting layer having an average thickness of35 nm was formed on the carrier trapping layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<6> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<7> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<8> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 14

A light emitting element was manufactured in the same manner as Example13 other than that a tris(8-quinolinolato)aluminium complex (Alq₃) wasused as the host material of the carrier trapping layer in step 4 ofExample 1, instead of the compound represented by the formula H2-30.

Example 15

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 40 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<4> Next, on the carrier trapping layer, an intermediate layer having anaverage thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<5> Next, on the intermediate layer, a blue light emitting layer havingan average thickness of 30 nm was formed by using the vacuum depositionmethod to vapor deposit the constituent materials of the blue lightemitting layer. As the constituent materials of the blue light emittinglayer, a compound (styrylamine based compound) represented by thechemical formula (24B) was used as the light emitting material (guestmaterial), and a compound (anthracene based material) represented by theformula H2-30 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in theblue light emitting layer was set to 6.0 wt %.

<6> Next, on the blue light emitting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (anthracene basedmaterial) represented by the formula H2-30 was used as the hostmaterial. In addition, the content (doping concentration) of thethiadiazole based compound (dopant) in the carrier trapping layer wasset to 3.0 wt %.

<7> Next, an electron transporting layer having an average thickness of35 nm was formed on the carrier trapping layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<8> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<9> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<10> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 16

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 50 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe red light emitting layer was vapor deposited with a vacuumdeposition method to form a red light emitting layer having an averagethickness of 20 nm. As the constituent materials of the red lightemitting layer, a compound (diindenoperylene derivative) represented bythe chemical formula (17) was used as the light emitting material (guestmaterial), and a compound (tetracene based material) represented by theformula H1-5 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in thered light emitting layer was set to 2.0 wt %.

<4> Next, an electron transporting layer having an average thickness of10 nm was formed on the red light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<5> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<6> Next, on the electron injection layer, a carrier generating layerhaving an average thickness of 10 nm configured by the compoundrepresented by the formula (50) was formed using the vacuum depositionmethod.

<7> Next, on the carrier generating layer, the amine based holetransporting material (tetrakis-p-biphenylyl benzidine) was vapordeposited with a vacuum deposition method to form a hole transportinglayer having an average thickness of 10 nm.

<8> Next, on the hole transporting layer, the constituent material ofthe carrier trapping layer was vapor deposited with a vacuum depositionmethod to form a carrier trapping layer having an average thickness of 5nm. As the constituent material of the carrier trapping layer, acompound represented by the formula D-11 was used as the thiadiazolebased compound (guest material), and a compound (tetracene basedmaterial) represented by the formula H1-5 was used as the host material.In addition, the content (doping concentration) of the thiadiazole basedcompound (dopant) in the carrier trapping layer was set to 3.0 wt %.

<9> Next, on the carrier trapping layer, an intermediate layer having anaverage thickness of 15 nm configured by the constituent materials ofthe intermediate layer shown below was formed using the vacuumdeposition method.

Here, as the constituent material of the first intermediate layer, acompound represented by the formula H2-30 was used as the host material,and tetrakis-p-biphenylyl benzidine was used as the amine basedmaterial. In addition, the content of the host material in theintermediate layer was set to 30 wt %.

<10> Next, on the intermediate layer, the constituent material of theblue light emitting layer was vapor deposited with a vacuum depositionmethod to form a blue light emitting layer having an average thicknessof 15 nm. As the constituent materials of the blue light emitting layer,a compound (styrylamine based compound) represented by the chemicalformula (24B) was used as the light emitting material (guest material),and a compound (anthracene based material) represented by the formulaH2-30 was used as the host material. In addition, the content (dopingconcentration) of the light emitting material (dopant) in the blue lightemitting layer was set to 5.0 wt %.

<11> Next, on the blue light emitting layer, a green light emittinglayer having an average thickness of 15 nm was formed by using thevacuum deposition method to vapor deposit the constituent materials ofthe green light emitting layer. As the constituent materials of thegreen light emitting layer, a compound (quinacridone derivative)represented by the chemical formula (25) was used as the light emittingmaterial (guest material), and a compound (anthracene based material)represented by the formula H2-30 was used as the host material. Inaddition, the content (doping concentration) of the light emittingmaterial (dopant) in the green light emitting layer was set to 6.0 wt %.

<12> Next, an electron transporting layer having an average thickness of25 nm was formed on the green light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<13> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<14> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<15> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Comparative Example 5

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the ITO electrode, the amine based hole transportingmaterial (tetrakis-p-biphenylyl benzidine) was vapor deposited with avacuum deposition method to form a hole transporting layer having anaverage thickness of 50 nm.

<3> Next, on the hole transporting layer, the constituent material ofthe red light emitting layer was vapor deposited with a vacuumdeposition method to form a red light emitting layer having an averagethickness of 20 nm. As the constituent materials of the red lightemitting layer, a compound (diindenoperylene derivative) represented bythe chemical formula (17) was used as the light emitting material (guestmaterial), and a compound (tetracene based material) represented by theformula H1-5 was used as the host material. In addition, the content(doping concentration) of the light emitting material (dopant) in thered light emitting layer was set to 2.0 wt %.

<4> Next, an electron transporting layer having an average thickness of10 nm was formed on the red light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<5> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<6> Next, on the electron injection layer, a carrier generating layerhaving an average thickness of 10 nm configured by the compoundrepresented by the formula (50) was formed using the vacuum depositionmethod.

<7> Next, on the carrier generating layer, the amine based holetransporting material (tetrakis-p-biphenylyl benzidine) was vapordeposited with a vacuum deposition method to form a hole transportinglayer having an average thickness of 30 nm.

<8> Next, on the carrier generating layer, the constituent material ofthe blue light emitting layer was vapor deposited with a vacuumdeposition method to form a blue light emitting layer having an averagethickness of 15 nm. As the constituent materials of the blue lightemitting layer, a compound (styrylamine based compound) represented bythe chemical formula (24B) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the blue light emitting layer was set to 5.0 wt %.

<9> Next, on the blue light emitting layer, a green light emitting layerhaving an average thickness of 15 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of thegreen light emitting layer. As the constituent materials of the greenlight emitting layer, a compound (quinacridone derivative) representedby the chemical formula (25) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the green light emitting layer was set to 6.0 wt %.

<10> Next, an electron transporting layer having an average thickness of25 nm was formed on the green light emitting layer by forming a filmwith the compound represented by the formula ETL-A3 using the vacuumdeposition method.

<11> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<12> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<13> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

Example 17

<1> First, a transparent glass substrate having an average thickness of0.5 mm was manufactured. Next, an ITO electrode (anode) having anaverage thickness of 100 nm was formed on this substrate using asputtering method.

Then, after the substrate was immersed in acetone and 2-propanol inorder and subjected to ultrasonic cleaning, oxygen plasma treatment andargon plasma treatment were performed. The above plasma treatments wererespectively performed with a plasma power of 100 W, a gas flow rate of20 sccm, and a treatment time of 5 seconds in a state where thesubstrate was heated to 70 to 90° C.

<2> Next, on the anode, the constituent material of the carrier trappinglayer was vapor deposited with a vacuum deposition method to form acarrier trapping layer having an average thickness of 60 nm. As theconstituent material of the carrier trapping layer, a compoundrepresented by the formula D-11 was used as the thiadiazole basedcompound (guest material), and tetrakis-p-biphenylyl benzidine was usedas the host material. In addition, the content (doping concentration) ofthe thiadiazole based compound (dopant) in the carrier trapping layerwas set to 3.0 wt %.

<3> Next, on the carrier trapping layer, a blue light emitting layerhaving an average thickness of 30 nm was formed by using the vacuumdeposition method to vapor deposit the constituent materials of the bluelight emitting layer. As the constituent materials of the blue lightemitting layer, a compound (styrylamine based compound) represented bythe chemical formula (24B) was used as the light emitting material(guest material), and a compound (anthracene based material) representedby the formula H2-30 was used as the host material. In addition, thecontent (doping concentration) of the light emitting material (dopant)in the blue light emitting layer was set to 6.0 wt %.

<4> Next, an electron transporting layer having an average thickness of40 nm was formed on the blue light emitting layer by forming a film withthe compound represented by the formula ETL-A3 using the vacuumdeposition method.

<5> Next, an electron injection layer having an average thickness of 1nm was formed on the electron transporting layer by forming a film withlithium fluoride (LiF) using the vacuum deposition method.

<6> Next, an Al film was formed on the electron injection layer usingthe vacuum deposition method. In this manner, a cathode, which had anaverage thickness of 150 nm and was configured of Al, was formed.

<7> Next, a protective cover (sealing member) made of glass was used asa cover so as to cover each of the formed layers and fixed and sealedusing epoxy resin.

Through the above steps, a light emitting element was manufactured.

3. Evaluation

For the light emitting elements of each Example and each ComparativeExample, a constant current of 100 mA/cm² was made to flow to the lightemitting elements using a constant current power source (Keithley 2400manufactured by TOYO Corporation) and the light emitting waveform atthat time was measured using a waveform measurement device (“S-2440”manufactured by Soma Optics, Ltd.).

The chromaticity (x, y) of the luminescent light at that time wasmeasured using a color meter (“CS-2000” manufactured by Konica MinoltaSensing Inc.) and the light emitting brightness (cd/m²) was measuredusing an optical power measuring device (“Optical Power Meter 8230”,manufactured by ADC Corporation).

In addition, for the light emitting elements of each Example and eachComparative Example respectively, a constant current of 100 mA/cm² wasmade to flow to the light emitting elements and the time (LT80) untilthe brightness became 80% of the initial brightness was measured.

The above measurement results are shown in Tables 1 to 5 and FIGS. 11 to16.

TABLE 1 Light Thiadiazole- Chromaticity emitting life Based (CIE 1931)Brightness span (LT80) Compound x y [cd/m²] [hr] Example 1 D-1 0.14 0.10400 450 Example 2 D-4 0.14 0.10 390 430 Example 3 D-7 0.14 0.10 390 440Example 4 D-10 0.14 0.10 395 460 Example 5 D-2 0.14 0.10 388 550 Example6 D-5 0.14 0.10 380 550 Example 7 D-8 0.14 0.10 360 480 Example 8 D-110.14 0.10 370 560 Example 9 D-11 0.14 0.10 400 300 Example 13 D-11 0.140.10 446 150 Example 14 D-11 0.14 0.10 332 100 Example 15 D-11 0.14 0.10346 580 Example 17 D-11 0.14 0.10 305 250 Comparative — 0.14 0.10 498 50Example 1

As is clear from Table 1 and FIGS. 11 to 14, in the light emittingelements of each Example emitting blue light as visible light, even in acase where the carrier trapping layer was arranged at any one of theanode side of the light emitting layer or the cathode side, it waspossible to emit blue light without changing the chromaticity incomparison with the light emitting element of Comparative Example 1 inwhich the forming of the carrier trapping layer was omitted.

In addition, as is clear from Table 1, it was determined that the lightemitting elements of each Example had a high light emitting brightness,and the life spans thereof were lengthened in comparison with the lightemitting element of Comparative Example 1.

TABLE 2 Light Thiadiazole- Chromaticity emitting life Based (CIE 1931)Brightness span (LT80) Compound x y [cd/m²] [hr] Example 10 D-11 0.480.51 689 570 Comparative — 0.48 0.51 792 150 Example 2

As is clear from Table 2 and FIG. 14, in the light emitting element ofExample 10 emitting yellow light as visible light, it was possible toemit yellow light without changing the chromaticity in comparison withthe light emitting element of Comparative Example 2 in which the formingof the carrier trapping layer was omitted.

Further, as is clear from Table 2, it was determined that the lightemitting element of Example 10 had a high light emitting brightness, andthe life span thereof was lengthened in comparison with the lightemitting element of Comparative Example 2.

TABLE 3 Light Thiadiazole- Chromaticity emitting life Based (CIE 1931)Brightness span (LT80) Compound x y [cd/m²] [hr] Example 11 D-11 0.270.33 702 580 Comparative — 0.27 0.33 815 300 Example 3

As is clear from Table 3 and FIG. 15, in the light emitting element ofExample 11 emitting white light (cyan light+yellow light) as visiblelight, it was possible to emit white light without changing thechromaticity in comparison with the light emitting element ofComparative Example 3 in which the forming of the carrier trapping layerwas omitted.

Further, as is clear from Table 3, it was determined that the lightemitting element of Example 11 had a high light emitting brightness, andthe life span thereof was lengthened in comparison with the lightemitting element of Comparative Example 3.

TABLE 4 Light Thiadiazole- Chromaticity emitting life Based (CIE 1931)Brightness span (LT80) Compound x y [cd/m²] [hr] Example 12 D-11 0.30.30 769 600 Comparative — 0.3 0.30 858 400 Example 4

As is clear from Table 4 and FIG. 15, in the light emitting element ofExample 12 emitting white light (red light+green light+blue light) asvisible light, it was possible to cause white light to be emittedwithout changing the chromaticity in comparison with the light emittingelement of Comparative Example 4 in which the forming of the carriertrapping layer was omitted.

Further, as is clear from Table 4, it was determined that the lightemitting element of Example 12 had a high light emitting brightness, andthe life span thereof was lengthened in comparison with the lightemitting element of Comparative Example 4.

TABLE 5 Light Thiadiazole- Chromaticity emitting life Based (CIE 1931)Brightness span (LT80) Compound x y [cd/m²] [hr] Example 16 D-11 0.280.32 1630 800 Comparative — 0.28 0.32 1839 170 Example 5

As is clear from Table 5 and FIG. 16, in the light emitting element ofExample 16 emitting white light (red light+green light+blue light) asvisible light, it was possible to cause white light to be emittedwithout changing the chromaticity in comparison with the light emittingelement of Comparative Example 5 in which the forming of the carriertrapping layer was omitted.

Further, as is clear from Table 5, it was determined that the lightemitting element of Example 16 had a high light emitting brightness, andthe life span thereof was lengthened in comparison with the lightemitting element of Comparative Example 5.

The present invention contains subject matter related to Japanese PatentApplication No. 2011-289851 filed in the Japanese Patent Office on Dec.28, 2011, and the entire contents of which are incorporated herein byreference.

What is claimed is:
 1. A light emitting element comprising: an anode; ancathode; a red light emitting layer; a blue light emitting layer; agreen light emitting layer; and an intermediate layer which isinterposed between the red light emitting layer and the blue lightemitting layer, the intermediate layer adjusts movement of the holes andelectrons between the red light emitting layer and the blue lightemitting layer.
 2. The light emitting element according to claim 1,further comprising: a carrier trapping layer, the carrier trapping layeris between the anode and the red light emitting layer.
 3. The lightemitting element according to claim 2: the intermediate layer includes ahost material of the carrier trapping layer.
 4. The light emittingelement according to claim 3: the host material includes acene basedmaterial.